Polyethylene compositions and closures made from them

ABSTRACT

A dual reactor solution process gives high density polyethylene compositions containing a first ethylene copolymer and a second ethylene copolymer and which have good processability, stiffness, and environmental stress crack resistance. The polyethylene compositions are suitable for compression molding or injection molding applications and are particularly useful in the manufacture of caps and closures for bottles.

CROSS REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.14/557,996 filed on Dec. 2, 2014, entitled “POLYETHYLENE COMPOSITIONSAND CLOSURES FOR BOTTLES”, which is herein incorporated by reference inits entirety and which is a continuation of U.S. application Ser. No.13/601,509, filed on Aug. 31, 2012, entitled “POLYETHYLENE COMPOSITIONSAND CLOSURES FOR BOTTLES”, which is herein incorporated by reference inits entirety.

The present invention relates to polyethylene compositions that areuseful in the manufacture of molded articles such as closures forbottles.

Polymer compositions useful for molding applications, specifically themanufacture of caps and closures for bottles are well known. Screwclosures for example, are typically made from polypropylene (PP) inorder to achieve the necessary cap strength, however, an inner linercomposed of a soft polymer is required to provide necessary sealproperties. The soft inner liner can be made from ethylene/vinyl acetate(EVA), polyvinyl chloride (PVC), butyl rubber or other suitablematerial. The two-part cap is costly, and single part constructions arepreferred to reduce cost.

Accordingly, one-piece closures, such as screw caps have more recentlybeen made from polyethylene resins. The use of high density resin isrequired if the closures are to have sufficient stiffness, while broadermolecular weight distributions are desirable to impart good flowproperties and to improve environmental stress crack resistance (ESCR).

Polyethylene blends produced with conventional Ziegler-Natta or Phillipstype catalysts systems can be made having suitably high density and ESCRproperties, see, for example, WO 00/71615 and U.S. Pat. No. 5,981,664.However, the use of conventional catalyst systems typically producessignificant amounts of low molecular weight polymer chains having highcomonomer contents, which results in resins having non-idealorganoleptic properties.

Examples of high density multimodal polyethylene blends made usingconventional catalyst systems for the manufacture of caps or closuresare taught in U.S. Patent Application Publication Nos. 2005/0004315A1;2005/0267249A1; as well as WO 2006/048253, WO 2006/048254, WO2007/060007; and EP 2,017,302A1. Further high density, multimodalpolyethylene blends made by employing conventional Ziegler-Nattacatalysts are disclosed in U.S. Patent Application Publication Nos.2009/0062463A1; 2009/0198018; 2009/0203848 and in WO 2007/130515, WO2008/136849 and WO 2010/088265.

In contrast to traditional catalysts, the use of so called single sitecatalysts (such as “metallocene” and “constrained geometry” catalysts)provides resin having lower catalyst residues and improved organolepticproperties as taught by U.S. Pat. No. 6,806,338. The disclosed resinsare suitable for use in molded articles. Further resins comprisingmetallocene catalyzed components and which are useful for moldingapplications are described in U.S. Pat. Nos. 7,022,770; 7,307,126;7,396,878 and 7,396,881 and 7,700,708.

U.S. Patent Application Publication No. 2011/0165357A1 discloses a blendof metallocene catalyzed resins which is suitable for use in pressureresistant pipe applications.

U.S. Patent Application Publication No. 2006/0241256A1 teaches blendsformulated from polyethylenes made using a hafnocene catalyst in theslurry phase.

A bimodal resin having a relatively narrow molecular weight distributionand long chain branching is described in U.S. Pat. No. 7,868,106. Theresin is made using a bis-indenyl type metallocene catalyst in a dualslurry loop polymerization process and can be used to manufacture capsand closures.

U.S. Pat. No. 6,642,313 discloses multimodal polyethylene resins whichare suitable for use in the manufacture of pipes. A dual reactorsolution process is used to prepare the resins in the presence of aphosphinimine catalyst.

Narrow molecular weight polyethylene blends comprising a metalloceneproduced polyethylene component and a Zielger-Natta or metalloceneproduced polyethylene component are reported in U.S. Pat. No. 7,250,474.The blends can be used in blow molding and injection moldingapplications such as for example, milk bottles and bottle capsrespectively.

In U.S. Pat. No. 8,022,143, we disclosed a resin composition having agood balance of toughness, ESCR, processability, and organolepticproperties for use in the manufacture of caps and closures. The resinswere made using a single site catalyst system in a dual reactor solutionprocess, to provide bimodal polyethylene compositions in which comonomerwas present in both a high and a low molecular weight component. Thedisclosed resins had a normal comonomer distribution in that the lowmolecular weight component had a larger amount of comonomer than did thehigh molecular weight component. We have now found that by adding morecomonomer to the high molecular weight component of these resins, we canimprove the ESCR properties. The polyethylene compositions provided bythe present invention also have good organoleptic properties, balancedrheological and mechanical properties and are suitable for use in themanufacture of closures for bottles, or containers or pouches.

Provided in one embodiment is a polyethylene composition that can beused in the manufacture of caps and closures for bottles, containers orpouches.

Provided in another embodiment is a polyethylene composition which hasan improved ESCR while maintaining low shear viscosity values at highshear rates which is desirable for high-speed injection or compressionmolding applications.

Embodiments of the invention include caps and closures comprising apolyethylene composition made by a two reactor solution phase processand a single site catalyst. Plaques made from the polyethylenecompositions have a good balance of mechanical, processing andorganoleptic properties.

Provided in another embodiment is a closure for bottles, containers orpouches, the closure comprising a bimodal polyethylene compositioncomprising:

-   -   (1) 10 to 70 wt % of a first ethylene copolymer having a melt        index, I₂, of less than 0.4 g/10 min; a molecular weight        distribution, M_(w)/M_(n), of less than 3.0; and a density of        from 0.920 to 0.955 g/cm³; and    -   (2) 90 to 30 wt % of a second ethylene copolymer having a melt        index I₂, of from 100 to 10,000 g/10 min; a molecular weight        distribution, M_(w)/M_(n), of less than 3.0; and a density        higher than the density of the first ethylene copolymer, but        less than 0.967 g/cm³;

wherein the density of the second ethylene copolymer is less than 0.037g/cm³ higher than the density of the first ethylene copolymer; the ratioof short chain branching in the first ethylene copolymer (SCB1) to theshort chain branching in the second ethylene copolymer (SCB2) is greaterthan 0.5; and wherein the bimodal polyethylene composition has amolecular weight distribution, M_(W)/M_(n), of from 3 to 11; a densityof at least 0.949 g/cm³; a melt index I₂, of from 0.4 to 5.0 g/10 min;an Mz of less than 400,000; a stress exponent of less than 1.50; and anESCR Condition B (10% IGEPAL) of at least 20 hours.

Provided in another embodiment is a process to prepare a polyethylenecomposition, the polyethylene composition comprising:

-   -   (1) 10 to 70 wt % of a first ethylene copolymer having a melt        index, I₂, of less than 0.4 g/10 min; a molecular weight        distribution, M_(w)/M_(n), of less than 3.0; and a density of        from 0.920 to 0.955 g/cm³; and    -   (2) 90 to 30 wt % of a second ethylene copolymer having a melt        index I₂, of from 100 to 10,000 g/10 min; a molecular weight        distribution, M_(w)/M_(n), of less than 3.0; and a density        higher than the density of the first ethylene copolymer, but        less than 0.967 g/cm³;

wherein the density of the second ethylene copolymer is less than 0.037g/cm³ higher than the density of the first ethylene copolymer; the ratioof short chain branching in the first ethylene copolymer (SCB1) to theshort chain branching in the second ethylene copolymer (SCB2) is greaterthan 0.5; and wherein the polyethylene composition has a molecularweight distribution, M_(W)/M_(n), of from 3 to 11; a density of at least0.949 g/cm³; a melt index I₂, of from 0.4 to 5.0 g/10 min; an Mz of lessthan 400,000; a stress exponent of less than 1.50; and an ESCR ConditionB (10% IGEPAL) of at least 20 hours;

the process comprising contacting at least one single sitepolymerization catalyst system with ethylene and at least onealpha-olefin comonomer under solution polymerization conditions in atleast two polymerization reactors.

Provided in another embodiment is a bimodal polyethylene compositioncomprising:

-   -   (1) 30 to 60 wt % of a first ethylene copolymer having a melt        index, I₂, of less than 0.4 g/10 min; a molecular weight        distribution, M_(w)/M_(n), of less than 2.7; and a density of        from 0.925 to 0.950 g/cm³; and    -   (2) 70 to 40 wt % of a second ethylene copolymer having a melt        index I₂, of from 100 to 10,000 g/10 min; a molecular weight        distribution, M_(w)/M_(n), of less than 2.7; and a density        higher than the density of the first ethylene copolymer, but        less than 0.966 g/cm³;

wherein the density of the second ethylene copolymer is less than 0.037g/cm³ higher than the density of the first ethylene copolymer; the ratioof short chain branching in the first ethylene copolymer (SCB1) to theshort chain branching in the second ethylene copolymer (SCB2) is greaterthan 0.5; and wherein the bimodal polyethylene composition has amolecular weight distribution, M_(W)/M_(n), of from 4.0 to 10.0; adensity of from 0.949 to 0.957 g/cm³; a melt index I₂, of from 0.4 to5.0 g/10 min; a comonomer content of less than 0.75 mol % as determinedby ¹³C NMR; an Mz of less than 400,000; a stress exponent of less than1.50; and an ESCR Condition B (10% IGEPAL) of at least 20 hours.

Provided in another embodiment is a closure, said closure comprising abimodal polyethylene composition comprising:

-   -   (1) 10 to 70 weight percent of a first ethylene copolymer having        a melt index I₂, of less than 0.4 g/10 min; a molecular weight        distribution M_(w)/M_(n), of less than 2.7; and a density of        from 0.920 to 0.955 g/cm³; and    -   (2) 90 to 30 weight percent of a second ethylene copolymer        having a melt index I₂, of from greater than 500 to 20,000 g/10        min; a molecular weight distribution M_(w)/M_(n), of less than        2.7; and a density higher than the density of said first        ethylene copolymer, but less than 0.967 g/cm³;

wherein the density of said second ethylene copolymer is less than 0.037g/cm³ higher than the density of said first ethylene copolymer; theratio (SCB1/SCB2) of the number of short chain branches per thousandcarbon atoms in said first ethylene copolymer (SCB1) to the number ofshort chain branches per thousand carbon atoms in said second ethylenecopolymer (SCB2) is greater than 1.0; and wherein said bimodalpolyethylene composition has a molecular weight distributionM_(w)/M_(n), of from 6 to 13; a density of at least 0.949 g/cm³; a meltindex I₂, of from 0.2 to 3.0 g/10 min; an M_(z) of less than 450,000; astress exponent of less than 1.50, and an ESCR Condition B (10% IGEPAL)of at least 200 hours.

Provided in another embodiment is a process to prepare a polyethylenecomposition, said polyethylene composition comprising:

-   -   (1) 10 to 70 weight percent of a first ethylene copolymer having        a melt index I₂, of less than 0.4 g/10 min; a molecular weight        distribution M_(w)/M_(n), of less than 2.7; and a density of        from 0.920 to 0.955 g/cm³; and    -   (2) 90 to 30 weight percent of a second ethylene copolymer        having a melt index I₂, of from greater than 500 to 20,000 g/10        min; a molecular weight distribution M_(w)/M_(n), of less than        2.7; and a density higher than the density of said first        ethylene copolymer, but less than 0.967 g/cm³;

wherein the density of said second ethylene copolymer is less than 0.037g/cm³ higher than the density of said first ethylene copolymer; theratio (SCB1/SCB2) of the number of short chain branches per thousandcarbon atoms in said first ethylene copolymer (SCB1) to the number ofshort chain branches per thousand carbon atoms in said second ethylenecopolymer (SCB2) is greater than 1.0; and wherein said bimodalpolyethylene composition has a molecular weight distributionM_(w)/M_(n), of from 6 to 13; a density of at least 0.949 g/cm³; a meltindex I₂, of from 0.2 to 3.0 g/10 min; an M_(z) of less than 450,000; astress exponent of less than 1.50, and an ESCR Condition B (10% IGEPAL)of at least 200 hours;

said process comprising contacting at least one single sitepolymerization catalyst system with ethylene and at least onealpha-olefin under solution polymerization conditions in at least twopolymerization reactors.

Provided in another embodiment is a bimodal polyethylene compositioncomprising:

-   -   (1) 10 to 70 weight percent of a first ethylene copolymer having        a melt index I₂, of less than 0.4 g/10 min; a molecular weight        distribution M_(w)/M_(n), of less than 2.7; and a density of        from 0.920 to 0.955 g/cm³; and    -   (2) to 30 weight percent of a second ethylene copolymer having a        melt index I₂, of from greater than 500 to 20,000 g/10 min; a        molecular weight distribution M_(w)/M_(n), of less than 2.7; and        a density higher than the density of said first ethylene        copolymer, but less than 0.967 g/cm³;

wherein the density of said second ethylene copolymer is less than 0.037g/cm³ higher than the density of said first ethylene copolymer; theratio (SCB1/SCB2) of the number of short chain branches per thousandcarbon atoms in said first ethylene copolymer (SCB1) to the number ofshort chain branches per thousand carbon atoms in said second ethylenecopolymer (SCB2) is greater than 1.0; and wherein said bimodalpolyethylene composition has a molecular weight distributionM_(w)/M_(n), of from 6 to 13; a density of at least 0.949 g/cm³; a meltindex I₂, of from 0.2 to 3.0 g/10 min; an M_(z) of less than 450,000; astress exponent of less than 1.50, and an ESCR Condition B (10% IGEPAL)of at least 200 hours.

In an embodiment of the invention, the bimodal polyethylene compositionhas an ESCR Condition B (10% IGEPAL) of at least 350 hours.

In an embodiment of the invention, the bimodal polyethylene compositionhas an ESCR Condition B (10% IGEPAL) of greater than 400 hours.

In an embodiment of the invention, the bimodal polyethylene compositionhas a molecular weight distribution, M_(w)/M_(n), of from 8 to 12.

In an embodiment of the invention, the bimodal polyethylene compositionhas melt index I₂, of from 0.4 to 2.0 g/10 min.

In an embodiment of the invention, the second ethylene copolymer has amelt index I₂ of greater than 650 g/10 min.

In an embodiment of the invention, the second ethylene copolymer has amelt is density of less than 0.965 g/cm³.

In an embodiment of the invention, the bimodal polyethylene compositionhas a z-average molecular weight distribution, Mz/Mw of less than 4.0

In an embodiment of the invention, the first ethylene copolymer has adensity of from 0.925 to 0.950 g/cm³.

In an embodiment of the invention, the bimodal polyethylene compositionhas a density of from 0.951 to 0.957 g/cm³.

In an embodiment of the invention, the density of the second ethylenecopolymer is less than 0.035 g/cm³ higher than the density of the firstethylene copolymer.

In an embodiment of the invention, the first and second ethylenecopolymers have a M_(w)/M_(n) of less than 2.5.

In an embodiment of the invention, the bimodal polyethylene compositionhas a composition distribution breadth index (CDBI₂₅) of greater than55% by weight.

In an embodiment of the invention, the second ethylene copolymer has amelt index, I₂ of from 1,000 to 20,000.

In an embodiment of the invention, the ratio (SCB1/SCB2) of the numberof short chain branches per thousand carbon atoms in the first ethylenecopolymer (SCB1) to the number of short chain branches per thousandcarbon atoms in the second ethylene copolymer (SCB2) is greater than1.5.

In an embodiment of the invention, the bimodal polyethylene compositioncomprises: from 30 to 60 wt % of the first ethylene copolymer; and from70 to 40 wt % of the second ethylene copolymer.

In an embodiment of the invention, the bimodal polyethylene compositionhas a shear viscosity ratio of 12.5.

In an embodiment of the invention, the bimodal polyethylene compositionhas a broadness factor defined as (M_(w)/M_(n))/(M_(z)/M_(w)) of atleast 2.75.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plot of the ESCR in hours (the ESCR B10 for a moldedplaque) against the 2% secant flexural modulus (MPa) for selectedinventive and comparative polyethylene composition examples.

FIG. 2 shows a plot of the ESCR in hours (the ESCR B10 for a moldedplaque) against the shear viscosity ratio (η₁₀/η₁₀₀₀ at 240° C.) forselected inventive and comparative polyethylene composition examples.

FIG. 3 shows a plot of the shear viscosity ratio (η₁₀/η₁₀₀₀ at 240° C.)against the notched Izod Impact Strength (J/m) for selected inventiveand comparative polyethylene composition examples.

FIG. 4 shows a plot of the shear viscosity ratio (η₁₀/η₁₀₀₀ at 240° C.)against the 2% secant flexural modulus (MPa) for selected inventive andcomparative polyethylene composition examples.

FIG. 5 shows the relationship between the shear thinning indexSHI_((1,100)) and the melt index, I₂ of polyethylene compositions of thecurrent invention.

FIG. 6 shows a gel permeation chromatograph for inventive polyethylenecompositions Nos 10-13.

FIG. 7 shows the relationship between the shear thinning indexSHI_((1,100)) and the melt index, I₂ of polyethylene compositions of thecurrent invention (inventive polyethylene composition examples Nos10-13).

DETAILED DESCRIPTION

The present invention is related to caps and closures for bottles orcontainer or pouches and to the polyethylene compositions used tomanufacture them. The polyethylene compositions are composed of at leasttwo ethylene copolymer components: a first ethylene copolymer and asecond ethylene copolymer. The polyethylene compositions of theinvention have a good balance of processability, toughness, stiffness,environmental stress crack resistance, and organoleptic propertiesmaking them ideal materials for use in manufacturing caps and closuresfor bottles or containers or pouches.

By the term “ethylene copolymer” it is meant that the copolymercomprises both ethylene and at least one alpha-olefin comonomer.

The terms “cap” and “closure” are used interchangeably in the currentinvention, and both connote any suitably shaped molded article forenclosing, sealing, closing or covering etc., a suitably shaped opening,a suitably molded aperture, an open necked structure or the like used incombination with a container, a bottle, a jar, a pouch and the like.

The terms “homogeneous” or “homogeneously branched polymer” as usedherein define homogeneously branched polyethylene which has a relativelynarrow composition distribution, as indicated by a relatively highcomposition distribution breadth index (CDBI₅₀). That is, the comonomeris randomly distributed within a given polymer chain and a substantialportion of the polymer chains have same ethylene/comonomer ratio.

It is well known that metallocene catalysts and other so called “singlesite catalysts” incorporate comonomer more evenly than traditionalZiegler-Natta catalysts when used for catalytic ethylenecopolymerization with alpha olefins. This fact is often demonstrated bymeasuring the composition distribution breadth index (CDBI₅₀) forcorresponding ethylene copolymers. The composition distribution of apolymer can be characterized by the short chain distribution index(SCDI) or composition distribution breadth index (CDBI₅₀). Thedefinition of composition distribution breadth index (CDBI₅₀) can befound in PCT publication WO 93/03093 and U.S. Pat. No. 5,206,075. TheCDBI₅₀ is conveniently determined using techniques which isolate polymerfractions based on their solubility (and hence their comonomer content).For example, temperature rising elution fractionation (TREF) asdescribed by Wild et al. J. Poly. Sci., Poly. Phys. Ed. Vol. 20, p 441,1982 or in U.S. Pat. No. 4,798,081 can be employed. From the weightfraction versus composition distribution curve, the CDBI₅₀ is determinedby establishing the weight percentage of a copolymer sample that has acomonomer content within 50% of the median comonomer content on eachside of the median. Generally, Ziegler-Natta catalysts produce ethylenecopolymers with a CDBI₅₀of less than about 50 weight %, or less thanabout 55 weight %, consistent with a heterogeneously branched copolymer.In contrast, metallocenes and other single site catalysts will mostoften produce ethylene copolymers having a CDBI₅₀ of greater than about55 weight %, or greater than about 60 weight %, consistent with ahomogeneously branched copolymer.

The First Ethylene Copolymer

In an embodiment of the invention, the first ethylene copolymer of thepolyethylene composition has a density of from about 0.920 g/cm³ toabout 0.955 g/cm³; a melt index, I₂, of less than about 0.4 g/10 min; amolecular weight distribution, M_(w)/M_(n), of below about 3.0 and aweight average molecular weight, M_(w), that is greater than the M_(w)of the second ethylene copolymer. In an embodiment of the invention, theweight average molecular weight, M_(w), of the first ethylene copolymeris at least 110,000.

In an embodiment of the invention, the first ethylene copolymer of thepolyethylene composition has a density of from about 0.920 g/cm³ toabout 0.955 g/cm³; a melt index, I₂, of less than about 0.4 g/10 min; amolecular weight distribution, M_(w)/M_(n), of below about 2.7 and aweight average molecular weight, M_(w), that is greater than the M_(w)of the second ethylene copolymer.

In an embodiment of the invention, the first ethylene copolymer is ahomogeneously branched copolymer.

In an embodiment of the invention, the first ethylene copolymer is madewith a single site catalyst, such as for example a phosphiniminecatalyst.

In an embodiment of the invention, the comonomer (i.e. alpha-olefin)content in the first ethylene copolymer can be from about 0.05 to about3.0 mol %. The comonomer content of the first ethylene polymer isdetermined by mathematical deconvolution methods applied to a bimodalpolyethylene composition (see the Examples section).

In embodiments of the invention, the comonomer in the first ethylenecopolymer is one or more olefin such as but not limited to 1-butene,1-hexene, 1-octene and the like.

In an embodiment of the invention, the first ethylene copolymer is acopolymer of ethylene and 1-octene.

In an embodiment of the invention, the short chain branching in thefirst ethylene copolymer can be from about 0.25 to about 15 short chainbranches per thousand carbon atoms (SCB 1/1000Cs). In furtherembodiments of the invention, the short chain branching in the firstethylene copolymer can be from 0.5 to 15, or from 0.5 to 12, or from 0.5to 10, or from 0.75 to 15, or from 0.75 to 12, or from 0.75 to 10, orfrom 1.0 to 10, or from 1.0 to 8.0, or from 1.0 to 5, or from 1.0 to 3branches per thousand carbon atoms (SCB 1/1000Cs). The short chainbranching is the branching due to the presence of alpha-olefin comonomerin the ethylene copolymer and will for example have two carbon atoms fora 1-butene comonomer, or four carbon atoms for a 1-hexene comonomer, orsix carbon atoms for a 1-octene comonomer, etc. The number of shortchain branches in the first ethylene copolymer is determined bymathematical deconvolution methods applied to a bimodal polyethylenecomposition (see the Examples section).

In an embodiment of the invention, the comonomer content in the firstethylene copolymer is substantially similar or approximately equal(e.g., within about ±0.01 mol %) to the comonomer content of the secondethylene copolymer (as reported, for example, in mol %).

In an embodiment of the invention, the comonomer content in the firstethylene copolymer is greater than comonomer content of the secondethylene copolymer (as reported for example in mol %).

In an embodiment of the invention, the amount of short chain branchingin the first ethylene copolymer is substantially similar orapproximately equal (e.g., within about ±0.05 SCB/1000 Cs) to the amountof short chain branching in the second ethylene copolymer (as reportedin short chain branches, SCB per thousand carbons in the polymerbackbone, 1000 Cs).

In an embodiment of the invention, the amount of short chain branchingin the first ethylene copolymer is greater than the amount of shortchain branching in the second ethylene copolymer (as reported in shortchain branches, SCB per thousand carbons in the polymer backbone, 1000Cs).

In an embodiment of the invention, the melt index, I₂ of the firstethylene copolymer is less than 0.4 g/10 min. The melt index of thefirst ethylene copolymer can in an embodiment of the invention be above0.01, but below 0.4 g/10 min. In further embodiments of the invention,the melt index, I₂ of the first ethylene copolymer will be from 0.01 to0.40 g/10 min, or from 0.01 to 0.30 g/10 min, or from 0.01 to 0.25 g/10min, or from 0.01 to 0.20 g/10 min, or from 0.01 to 0.10 g/10 min.

In an embodiment of the invention, the first ethylene copolymer has aweight average molecular weight M_(w) of from about 110,000 to about300,000 (g/mol). In another embodiment of the invention, the firstethylene copolymer has a weight average molecular weight M_(w) of fromabout 110,000 to about 275,000 or from about 110,000 to about 250,000.In another embodiment of the invention, the first ethylene copolymer hasa weight average molecular weight M_(w) of greater than about 110,000 toless than about 250,000. In further embodiments of the invention, thefirst ethylene copolymer has a weight average molecular weight M_(w) offrom about 125,000 to about 225,000, or from about 135,000 to about200,000. In embodiments of the invention, the first ethylene copolymerhas a weight average molecular weight M_(w) of from about 125,000 toabout 275,000, or from about 125,000 to about 250,000, or from about150,000 to about 275,000, or from about 150,000 to about 250,000, orfrom about 175,000 to about 250,000. In embodiments of the invention,the first ethylene copolymer has a M_(w) of greater than 110,000, orgreater than 125,000, or greater than 150,000, or greater than 175,000.In embodiments of the invention the first ethylene copolymer has a M_(w)of greater than 110,000, or greater than 125,000, or greater than150,000, or greater than 175,000 while at the same time being lower than275,000, or 250,000.

In embodiments of the invention, the density of the first ethylenecopolymer is from 0.920 to 0.955 g/cm³ or can be a narrower range withinthis range. For example, in further embodiments of the invention, thedensity of the first ethylene copolymer can be from 0.925 to 0.955g/cm³, or from 0.925 to 0.950 g/cm³, or from 0.925 to 0.945 g/cm³, orfrom 0.925 to 0.940 g/cm³, or from 0.925 to 0.935 g/cm³, or from 0.923to 0.945 g/cm³, or from 0.923 to 0.940 g/cm³, or from 0.923 to 0.935g/cm³, or from 0.927 to 0.945 g/cm³, or from 0.927 to 0.940 g/cm³, orfrom 0.927 to 0.935 g/cm³.

In an embodiments of the invention, the first ethylene copolymer has amolecular weight distribution M_(w)/M_(n) of <3.0, or ≦2.7, or <2.7, or≦2.5, or <2.5, or ≦2.3, or from 1.8 to 2.3.

The M_(w)/M_(n) value of the first ethylene copolymer can in anembodiment of the invention be estimated by a de-covolution of a GPCprofile obtained for a bimodal polyethylene composition of which thefirst ethylene copolymer is a component.

The density and the melt index, I₂, of the first ethylene copolymer canbe estimated from GPC (gel permeation chromatography) and GPC-FTIR (gelpermeation chromatography with Fourier transform infra-red detection)experiments and deconvolutions carried out on the bimodal polyethylenecomposition (see the Examples section).

In an embodiment of the invention, the first ethylene copolymer of thepolyethylene composition is a homogeneously branched ethylene copolymerhaving a weight average molecular weight, M_(w), of at least 110,000; amolecular weight distribution, M_(w)/M_(n), of less than 2.7 and adensity of from 0.920 to 0.948 g/cm³.

In an embodiment of the present invention, the first ethylene copolymeris homogeneously branched ethylene copolymer and has a CDBI₅₀ of greaterthan about 50%, or greater than about 55% by weight. In furtherembodiments of the invention, the first ethylene copolymer has a CDBI ofgreater than about 60%, or greater than about 65%, or greater than about70%, or greater than about 75%, or greater than about 80% by weight.

In an embodiment of the invention, the first ethylene copolymer cancomprise from 10 to 70 weight percent (wt %) of the total weight of thefirst and second ethylene copolymers. In an embodiment of the invention,the first ethylene copolymer comprises from 20 to 60 weight percent (wt%) of the total weight of the first and second ethylene copolymers. Inan embodiment of the invention, the first ethylene copolymer comprisesfrom 30 to 60 weight percent (wt %) of the total weight of the first andsecond ethylene copolymers. In an embodiment of the invention, the firstethylene copolymer comprises from 40 to 50 weight percent (wt %) of thetotal weight of the first and second ethylene copolymers.

The Second Ethylene Copolymer

In an embodiment of the invention, the second ethylene copolymer of thepolyethylene composition has a density below 0.967 g/cm³ but which ishigher than the density of the first ethylene copolymer; a melt index,I₂, of from about 100 to 10,000 g/10 min; a molecular weightdistribution, M_(w)/M_(n), of below about 3.0 and a weight averagemolecular weight M_(w) that is less than the M_(w) of the first ethylenecopolymer. In an embodiment of the invention, the weight averagemolecular weight, M_(w) of the second ethylene copolymer will be below45,000.

In an embodiment of the invention, the second ethylene copolymer of thepolyethylene composition has a density below 0.967 g/cm³ but which ishigher than the density of the first ethylene copolymer; a melt index,I₂, of from about 500 to about 20,000 g/10 min; a molecular weightdistribution, M_(w)/M_(n), of below about 2.7, and a weight averagemolecular weight M_(w) that is less than the M_(w) of the first ethylenecopolymer.

In an embodiment of the invention, the second ethylene copolymer ishomogeneously branched copolymer.

In an embodiment of the invention, the second ethylene copolymer is madewith a single site catalyst, such as for example a phosphiniminecatalyst.

In an embodiment of the invention, the comonomer content in the secondethylene copolymer can be from about 0.05 to about 3 mol % as measuredby ¹³C NMR, or FTIR or GPC-FTIR methods. The comonomer content of thesecond ethylene polymer can also be determined by mathematicaldeconvolution methods applied to a bimodal polyethylene composition (seethe Examples section).

In an embodiment of the invention, the comonomer content in the secondethylene copolymer can be from about 0.01 to about 3 mol %, or fromabout 0.03 to about 3 mol % as measured by ¹³C NMR, or FTIR or GPC-FTIRmethods. The comonomer content of the second ethylene polymer can alsobe determined by mathematical deconvolution methods applied to a bimodalpolyethylene composition (see the Examples section).

In an embodiment of the invention, the comonomer in the second ethylenecopolymer is one or more alpha olefin such as but not limited to1-butene, 1-hexene, 1-octene and the like.

In an embodiment of the invention, the second ethylene copolymer is acopolymer of ethylene and 1-octene.

In an embodiment of the invention, the short chain branching in thesecond ethylene copolymer can be from about 0.25 to about 15 short chainbranches per thousand carbon atoms (SCB 2/1000Cs). In furtherembodiments of the invention, the short chain branching in the secondethylene copolymer can be from 0.25 to 12, or from 0.25 to 8, or from0.25 to 5, or from 0.25 to 3, or from 0.25 to 2 branches per thousandcarbon atoms (SCB 2/1000Cs). The short chain branching is the branchingdue to the presence of alpha-olefin comonomer in the ethylene copolymerand will for example have two carbon atoms for a 1-butene comonomer, orfour carbon atoms for a 1-hexene comonomer, or six carbon atoms for a1-octene comonomer, etc. The number of short chain branches in thesecond ethylene copolymer can be measured by ¹³C NMR, or FTIR orGPC-FTIR methods. Alternatively, the number of short chain branches inthe second ethylene copolymer can be determined by mathematicaldeconvolution methods applied to a bimodal polyethylene composition (seethe Examples section). The comonomer is one or more suitable alphaolefin such as but not limited to 1-butene, 1-hexene, 1-octene and thelike, with 1-octene being preferred.

In an embodiment of the invention, the short chain branching in thesecond ethylene copolymer can be from about 0.05 to about 12 short chainbranches per thousand carbon atoms (SCB 1/1000Cs). In furtherembodiments of the invention, the short chain branching in the secondethylene copolymer can be from 0.05 to 7.5, or from 0.05 to 5.0, or from0.05 to 2.5, or from 0.05 to 1.5, or from 0.1 to 12, or from 0.1 to 10,or from 0.1 to 7.5, or from 0.1 to 5.0, or from 0.1 to 2.5, or from 0.1to 2.0, or from 0.1 to 1.0 branches per thousand carbon atoms (SCB1/1000Cs).

In an embodiment of the invention, the comonomer content in the secondethylene copolymer is substantially similar or approximately equal(e.g., within about ±0.01 mol %) to the comonomer content of the firstethylene copolymer (as reported, for example, in mol %).

In an embodiment of the invention, the comonomer content in the secondethylene copolymer is less than the comonomer content of the firstethylene copolymer (as reported for example in mol %).

In an embodiment of the invention, the amount of short chain branchingin the second ethylene copolymer is substantially similar orapproximately equal (e.g. within about ±0.05 SCB/1000C) to the amount ofshort chain branching in the first ethylene copolymer (as reported inshort chain branches, SCB per thousand carbons in the polymer backbone,1000 Cs).

In an embodiment of the invention, the amount of short chain branchingin the second ethylene copolymer is less than the amount of short chainbranching in the first ethylene copolymer (as reported in short chainbranches, SCB per thousand carbons in the polymer backbone, 1000 Cs).

In an embodiment of the present invention, the density of the secondethylene copolymer is less than 0.967 g/cm³. The density of the secondethylene copolymer in another embodiment of the invention is less than0.966 g/cm³. In another embodiment of the invention, the density of thesecond ethylene copolymer is less than 0.965 g/cm³. In anotherembodiment of the invention, the density of the second ethylenecopolymer is less than 0.964 g/cm³. In another embodiment of theinvention, the density of the second ethylene copolymer is less than0.963 g/cm³. In another embodiment of the invention, the density of thesecond ethylene copolymer is less than 0.962 g/cm³.

In an embodiment of the present invention, the density of the secondethylene copolymer is higher than the density of the first ethylenecopolymer, but is less than 0.967 g/cm³. The density of the secondethylene copolymer in another embodiment of the invention is higher thanthe density of the first ethylene copolymer, but is less than 0.966g/cm³. In another embodiment of the invention, the density of the secondethylene copolymer is higher than the density of the first ethylenecopolymer, but is less than 0.965 g/cm³. In another embodiment of theinvention, the density of the second ethylene copolymer is higher thanthe density of the first ethylene copolymer, but is less than 0.964g/cm³. In another embodiment of the invention, the density of the secondethylene copolymer is higher than the density of the first ethylenecopolymer, but is less than 0.963 g/cm³. In another embodiment of theinvention, the density of the second ethylene copolymer is higher thanthe density of the first ethylene copolymer, but is less than 0.962g/cm³.

In an embodiment of the invention, the density of the second ethylenecopolymer is from 0.952 to 0.967 g/cm³ or can be a narrower range withinthis range. For example, the density of the second ethylene copolymermay in embodiments of the invention be from 0.952 to 0.966 g/cm³, 0.952to 0.965 g/cm³, or from 0.952 to 0.964 g/cm³, or from 0.952 to 0.963g/cm³, or from 0.954 to 0.963 g/cm³, or from 0.954 to 0.964 g/cm³, orfrom 0.956 to 0.964 g/cm³, or from 0.952 to less than 0.965 g/cm³, orfrom 0.954 to less than 0.965 g/cm³.

In an embodiment of the invention, the second ethylene copolymer has aweight average molecular weight M_(w) of less than 25,000. In anotherembodiment of the invention, the second ethylene copolymer has a weightaverage molecular weight M_(w) of from about 7,500 to about 23,000. Infurther embodiments of the invention, the second ethylene copolymer hasa weight average molecular weight M_(w) of from about 9,000 to about22,000, or from about 10,000 to about 17,500, or from about 7,500 toabout 17,500. In still further embodiments of the invention, the secondethylene copolymer has a weight average molecular weight M_(w) of fromabout 3,500 to about 25,000, or from about 5,000 to about 20,000, orfrom about 7,500 to about 17,500, or from about 5,000 to about 15,000,or from about 5,000 to about 17,500, or from about 7,500 to about 15,000or from about 7,500 to about 12,500. In further embodiments of theinvention, the second ethylene copolymer has a weight average molecularweight M_(w) of from about 9,000 to about 22,000, or from about 10,000to about 17,500, or from about 7,500 to 17,500.

In embodiments of the invention, the second ethylene copolymer has amolecular weight distribution, M_(w)/M_(n) of <3.0, or ≦2.7, or <2.7, or≦2.5, or <2.5, or ≦2.3, or from 1.8 to 2.3.

The Mw/Mn value of the second ethylene copolymer can in an embodiment ofthe invention be estimated by a de-convolution of a GPC profile obtainedfor a bimodal polyethylene composition of which the first ethylenecopolymer is a component.

In an embodiment of the invention, the melt index I₂ of the secondethylene copolymer can be from 20 to 10,000 g/10 min. In anotherembodiment of the invention, the melt index I₂ of the second ethylenecopolymer can be from 100 to 10,000 g/10 min. In yet another embodimentof the invention, the melt index I₂ of the second ethylene copolymer canbe from 1000 to 7000 g/10 min. In yet another embodiment of theinvention, the melt index I₂ of the second ethylene copolymer can befrom 1200 to 10,000 g/10 min. In yet another embodiment of theinvention, the melt index I₂ of the second ethylene copolymer can befrom 1500 to 10,000 g/10 min. In yet another embodiment of theinvention, the melt index I₂ of the second ethylene copolymer can begreater than 1500, but less than 7000 g/10 min.

In an embodiment of the invention, the melt index I₂ of the secondethylene copolymer can be from 250 to 20,000 g/10 min. In anotherembodiment of the invention, the melt index I₂ of the second ethylenecopolymer can be from 500 to 20,000 g/10 min. In another embodiment ofthe invention, the melt index I₂ of the second ethylene copolymer can befrom greater than 750 to 20,000 g/10 min. In further embodiments of theinvention, the melt index I₂ of the second ethylene copolymer can befrom 1000 to 20,000 g/10 min, or from 1,500 to 20,000 g/10 min, or from250 to 15,000 g/10 min, or from 250 to 10,000 g/10 min or from 500 to17,500 g/10 min, or from 500 to 15,000 g/10 min, or from 1,500 to 15,000g/10 min. In yet another embodiment of the invention, the melt index I₂of the second ethylene copolymer can be from 1200 to 10,000 g/10 min. Inyet another embodiment of the invention, the melt index I₂ of the secondethylene copolymer can be from 1500 to 10,000 g/10 min. In yet anotherembodiment of the invention, the melt index I₂ of the second ethylenecopolymer can be greater than 1500, but less than 7000 g/10 min.

In an embodiment of the invention, the melt index I₂ of the secondethylene copolymer is greater than 200 g/10 min. In an embodiment of theinvention, the melt index I₂ of the second ethylene copolymer is greaterthan 250 g/10 min. In an embodiment of the invention, the melt index I₂of the second ethylene copolymer is greater than 500 g/10 min. In anembodiment of the invention, the melt index I₂ of the second ethylenecopolymer is greater than 650 g/10 min. In an embodiment of theinvention, the melt index I₂ of the second ethylene copolymer is greaterthan 1000 g/10 min. In an embodiment of the invention, the melt index I₂of the second ethylene copolymer is greater than 1200 g/10 min. In anembodiment of the invention, the melt index I₂ of the second ethylenecopolymer is greater than 1500 g/10 min. In an embodiment of theinvention, the melt index I₂ of the second ethylene copolymer is greaterthan 1750 g/10 min.

The density and the melt index, I₂, of the second ethylene copolymer canbe estimated from GPC and GPC-FTIR experiments and deconvolutionscarried out on a bimodal polyethylene composition (see the belowExamples section).

In an embodiment of the invention, the second ethylene copolymer of thepolyethylene composition is a homogeneous ethylene copolymer having aweight average molecular weight, Mw, of at most 45000; a molecularweight distribution, M_(w)/M_(n), of less than 2.7 and a density higherthan the density of said first ethylene copolymer, but less than 0.967g/cm³.

In an embodiment of the present invention, the second ethylene copolymeris homogeneously branched ethylene copolymer and has a CDBI₅₀ of greaterthan about 50 weight %, or of greater than about 55 weight %. In furtherembodiments of the invention, the second ethylene copolymer has a CDBI₅₀of greater than about 60 weight %, or greater than about 65 weight %, orgreater than about 70 weight %, or greater than about 75 weight %, orgreater than about 80 weight %.

In an embodiment of the invention, the second ethylene copolymer cancomprise from 90 to 30 weight % (wt %) of the total weight of the firstand second ethylene copolymers. In an embodiment of the invention, thesecond ethylene copolymer comprises from 80 to 40 wt % of the totalweight of the first and second ethylene copolymers. In an embodiment ofthe invention, the second ethylene copolymer comprises from 70 to 40 wt% of the total weight of the first and second ethylene copolymers. In anembodiment of the invention, the second ethylene copolymer comprisesfrom 60 to 50 wt % of the total weight of the first and second ethylenecopolymers.

In the present invention, the second ethylene copolymer has a densitywhich is higher than the density of the first ethylene copolymer, butless than about 0.037 g/cm³ higher than the density of the firstethylene copolymer. In an embodiment of the invention, the secondethylene copolymer has a density which is higher than the density of thefirst ethylene copolymer, but less than about 0.036 g/cm³ higher thanthe density of the first ethylene copolymer. In an embodiment of theinvention, the second ethylene copolymer has a density which is higherthan the density of the first ethylene copolymer, but less than about0.035 g/cm³ higher than the density of the first ethylene copolymer. Inan embodiment of the invention, the second ethylene copolymer has adensity which is higher than the density of the first ethylenecopolymer, but less than about 0.034 g/cm³ higher than the density ofthe first ethylene copolymer. In an embodiment of the invention, thesecond ethylene copolymer has a density which is higher than the densityof the first ethylene copolymer, but less than about 0.033 g/cm³ higherthan the density of the first ethylene copolymer. In an embodiment ofthe invention, the second ethylene copolymer has a density which ishigher than the density of the first ethylene copolymer, but less thanabout 0.032 g/cm³ higher than the density of the first ethylenecopolymer. In another embodiment of the invention, the second ethylenecopolymer has a density which is higher than the density of the firstethylene copolymer, but less than about 0.031 g/cm³ higher than thedensity of the first ethylene copolymer. In still another embodiment ofthe invention, the second ethylene copolymer has a density which ishigher than the density of the first ethylene copolymer, but less thanabout 0.030 g/cm³ higher than the density of the first ethylenecopolymer.

In embodiments of the invention, the 12 of the second ethylene copolymeris at least 100 times, or at least 1000 times, or at least 10,000, or atleast 50,000 times the 12 of the first ethylene copolymer.

The Polyethylene Composition

The polyethylene composition of this invention has a broad, bimodal ormultimodal molecular weight distribution. Minimally, the polyethylenecomposition will contain a first ethylene copolymer and a secondethylene copolymer (as defined above) which are of different weightaverage molecular weight (M_(w)) and/or melt index, I₂.

In the present invention, the polyethylene composition will minimallycomprise a first ethylene copolymer and a second ethylene copolymer (asdefined above) and the ratio (SCB1/SCB2) of the number of short chainbranches per thousand carbon atoms in the first ethylene copolymer(i.e., SCB1) to the number of short chain branches per thousand carbonatoms in the second ethylene copolymer (i.e., SCB2) will be greater than0.5 (i.e., SCB1/SCB2>0.5).

In an embodiment of the invention, the ratio of the short chainbranching in the first ethylene copolymer (SCB1) to the short chainbranching in the second ethylene copolymer (SCB2) is at least 0.60. Inan embodiment of the invention, the ratio of the short chain branchingin the first ethylene copolymer (SCB1) to the short chain branching inthe second ethylene copolymer (SCB2) is at least 0.75. In anotherembodiment of the invention, the ratio of the short chain branching inthe first ethylene copolymer (SCB1) to the short chain branching in thesecond ethylene copolymer (SCB2) is at least 1.0. In another embodimentof the invention, the ratio of the short chain branching in the firstethylene copolymer (SCB1) to the short chain branching in the secondethylene copolymer (SCB2) is at greater than 1.0. In yet anotherembodiment of the invention, the ratio of the short chain branching inthe first ethylene copolymer (SCB1) to the short chain branching in thesecond ethylene copolymer (SCB2) is at least 1.25. In still furtherembodiments of the invention, the ratio of the short chain branching inthe first ethylene copolymer (SCB1) to the short chain branching in thesecond ethylene copolymer (SCB2) is at least 1.5, or at least 2.0, or atleast 2.5, or at least 3.0, or at least 3.5, or at least 4.0 or at least4.5.

In an embodiment of the invention, the ratio of the short chainbranching in the first ethylene copolymer (SCB1) to the short chainbranching in the second ethylene copolymer (SCB2) will be greater than0.5, but less than 1.0.

In embodiments of the invention, the ratio (SCB1/SCB2) of the shortchain branching in the first ethylene copolymer (SCB1) to the shortchain branching in the second ethylene copolymer (SCB2) will be from 1.0to 12.0, or from 1.0 to 10, or from 1.0 to 7.0, or from 1.0 to 5.0, orfrom 1.0 to 3.0.

In embodiments of the invention, the ratio (SCB1/SCB2) of the shortchain branching in the first ethylene copolymer (SCB1) to the shortchain branching in the second ethylene copolymer (SCB2) will be from 1.0to 15.0, or from 2.0 to 12.0, or from 2.5 to 12.0, or from 3.0 to 12.0,or from 3.5 to 12.0.

In ah embodiment of the invention, the polyethylene composition has abimodal molecular weight distribution. In the current invention, theterm “bimodal” means that the polyethylene composition comprises atleast two components, one of which has a lower weight average molecularweight and a higher density and another of which has a higher weightaverage molecular weight and a lower density. Typically, a bimodal ormultimodal polyethylene composition can be identified by using gelpermeation chromatography (GPC). Generally, the GPC chromatograph willexhibit two or more component ethylene copolymers, where the number ofcomponent ethylene copolymers corresponds to the number of discerniblepeaks. One or more component ethylene copolymers may also exist as ahump, shoulder or tail relative to the molecular weight distribution ofthe other ethylene copolymer component.

In an embodiment of the invention, the polyethylene composition has adensity of greater than or equal to 0.949 g/cm³, as measured accordingto ASTM D792; a melt index, I₂, of from about 0.4 to about 5.0 g/10 min,as measured according to ASTM D1238 (when conducted at 190° C., using a2.16 kg weight); a molecular weight distribution, M_(w)/M_(n), of fromabout 3 to about 11, a Z-average molecular weight, M_(z) of less than400,000, a stress exponent of less than 1.50 and an ESCR Condition B at10% of at least 20 hours.

In an embodiment of the invention, the polyethylene composition of thecurrent invention has a density of greater than or equal to 0.949 g/cm³,as measured according to ASTM D792; a melt index, I₂, of from about 0.2to about 5.0 g/10 min, as measured according to ASTM D1238 (whenconducted at 190° C., using a 2.16 kg weight); a molecular weightdistribution, M_(w)/M_(n), of from about 6 to about 13, a Z-averagemolecular weight, M_(z) of less than 450,000, a stress exponent of lessthan 1.50 and an ESCR Condition B at 10% of at least 200 hours.

In embodiments of the invention, the polyethylene composition has acomonomer content of less than 0.75 mol %, or less than 0.70 mol %, orless than 0.65 mol %, or less than 0.60 mol %, or less than 0.55 mol %as measured by FTIR or ¹³C NMR methods, with ¹³C NMR being preferred,where the comonomer is one or more suitable alpha olefins such as butnot limited to 1-butene, 1-hexene, 1-octene and the like. In anembodiment of the invention, the polyethylene composition has acomonomer content of from 0.1 to 0.75 mol %, or from 0.20 to 0.55 mol %,or from 0.25 to 0.50 mol %.

In the present invention, the polyethylene composition has a density ofat least 0.949 g/cm³. In further embodiments of the invention, thepolyethylene composition has a density of >0.949 g/cm³, or ≧0.950 g/cm³,or >0.950 g/cm³.

In an embodiment of the current invention, the polyethylene compositionhas a density in the range of from 0.949 to 0.960 g/cm³.

In an embodiment of the current invention, the polyethylene compositionhas a density in the range of from 0.949 to 0.959 g/cm³.

In an embodiment of the current invention, the polyethylene compositionhas a density in the range of from 0.949 to 0.957 g/cm³.

In an embodiment of the current invention, the polyethylene compositionhas a density in the range of from 0.949 to 0.956 g/cm³.

In an embodiment of the current invention, the polyethylene compositionhas a density in the range of from 0.949 to 0.955 g/cm³.

In an embodiment of the current invention, the polyethylene compositionhas a density in the range of from 0.950 to 0.955 g/cm³.

In an embodiment of the current invention, the polyethylene compositionhas a density in the range of from 0.951 to 0.957 g/cm³.

In an embodiment of the current invention, the polyethylene compositionhas a density in the range of from 0.951 to 0.955 g/cm³.

In an embodiment of the invention, the polyethylene composition has amelt index, I₂, of between 0.4 and 5.0 g/10 min according to ASTM D1238(when conducted at 190° C., using a 2.16 kg weight) and includingnarrower ranges within this range. For example, in further embodimentsof the invention, the polyethylene composition has a melt index, I₂, offrom 0.5 to 5.0 g/10 min, or from 0.4 to 3.5 g/10 min, or from 0.4 to3.0 g/10 min, or from 0.4 to 2.5 g/10 min, or from 0.4 to 2.0 g/10 min,or from 0.5 to 3.5 g/10 min, or from 0.5 to 3.0 g/10 min, or from 1.0 to3.0 g/10 min, or from about 1.0 to about 2.0 g/10 min, or from more than0.5 to less than 2.0 g10/min.

In an embodiment of the invention, the polyethylene composition has amelt index, I₂, of between 0.1 and 5.0 g/10 min according to ASTM D1238(when conducted at 190° C., using a 2.16 kg weight) and includingnarrower ranges within this range. For example, in further embodimentsof the invention, the polyethylene composition has a melt index, I₂, offrom 0.2 to 5.0 g/10 min, or from 0.3 to 4.0 g/10 min, or from 0.3 to3.5 g/10 min, or from 0.3 to 3.0 g/10 min, or from 0.2 to 3.5 g/10 min,or from 0.2 to 3.0 g/10 min, or from 0.1 to 2.5 g/10 min, or from 0.1 to2.0 g/10 min.

In an embodiment of the invention, the polyethylene composition has amelt index 15 of at least 1.0 g/10 min according to ASTM D1238 (whenconducted at 190° C., using a 5 kg weight). In another embodiment of theinvention, the polyethylene composition has a melt index, I₅, of greaterthan about 1.1 g/10 min, as measured according to ASTM D1238 (whenconducted at 190° C., using a 5 kg weight). In still further embodimentsof the invention, the polyethylene composition has a melt index 15 offrom about 1.0 to about 10.0 g/10 min, or from about 2.0 to about 8.0g/10 min, or from about 1.0 to about 5.0 g/10 min, or from about 1.5 toabout 6.5 g/10 min, or from about 4.0 to about 7.0 g/10 min, or fromabout 3.0 to about 6.5 g/10 min.

In an embodiment of the invention, the polyethylene composition has ahigh load melt index, I₂₁ of at least 25 g/10 min according to ASTMD1238 (when conducted at 190° C., using a 21 kg weight). In anotherembodiment of the invention, the polyethylene composition has a highload melt index, I₂₁, of greater than about 30 g/10 min. In yet anotherembodiment of the invention, the polyethylene composition has a highload melt index, I₂₁, of greater than about 35 g/10 min. In stillanother embodiment of the invention, the polyethylene composition has ahigh load melt index, I₂₁, of greater than about 40 g/10 min. In stillanother embodiment of the invention, the polyethylene composition has ahigh load melt index, I₂₁, of greater than about 50 g/10 min. In stillanother embodiment of the invention, the polyethylene composition has ahigh load melt index, I₂₁, of greater than about 60 g/10 min. In stillanother embodiment of the invention, the polyethylene composition has ahigh load melt index, I₂₁, of greater than about 75 g/10 min.

In an embodiment of the invention, the ratio of the melt index, I₂, ofthe second ethylene copolymer to the melt index, I₅, of the polyethylenecomposition is from 200 to 1500. In another embodiment of the invention,the ratio of the melt index, I₂, of the second ethylene copolymer to themelt index, I₅, of the polyethylene composition is from 400 to 1300. Inyet another embodiment of the invention, the ratio of the melt index,I₂, of the second ethylene copolymer to the melt index, I₅, of thepolyethylene composition is from 600 to 1200.

In an embodiment of the invention, the ratio of the melt index, I₂, ofthe second ethylene copolymer to the melt index, I₅, of the polyethylenecomposition is from 500 to 5000. In another embodiment of the invention,the ratio of the melt index, I₂, of the second ethylene copolymer to themelt index, I₅, of the polyethylene composition is from 750 to 4500. Inyet another embodiment of the invention, the ratio of the melt index,I₂, of the second ethylene copolymer to the melt index, I₅, of thepolyethylene composition is from 1000 to 4000.

In an embodiment of the invention, the polyethylene composition has acomplex viscosity, η* at a shear stress (G*) anywhere between from about1 to about 10 kPa which is between 1,000 to 25,000 Pa·s. In anembodiment of the invention, the polyethylene composition has a complexviscosity, η* at a shear stress (G*) anywhere from about 1 to about 10kPa which is between 1,000 and 10,000 Pa·s.

In an embodiment of the invention, the polyethylene composition has acomplex viscosity, η* at a shear stress (G*) anywhere between from about1 to about 10 kPa which is between 1,000 and 25,000 Pa·s. In anembodiment of the invention, the polyethylene composition has a complexviscosity, η* at a shear stress (G*) anywhere from about 1 to about 10kPa which is between 1,000 and 10,000 Pa·s, or between 1,000 and 15,000Pa·s, or from 3,000 to 12,500 Pa·s.

In an embodiment of the invention, the polyethylene composition has anumber average molecular weight, M_(n), of below about 30,000. Inanother embodiment of the invention, the polyethylene composition has anumber average molecular weight, M_(n), of below about 20,000 or belowabout 17,500. In further embodiments of the invention, the polyethylenecomposition has a number average molecular weight, M_(n), of from about5,000 to 25,000, or from about 5,000 to 20,000, or from about 7,000 toabout 15,000.

In embodiments of the invention, the polyethylene composition has aweight average molecular weight, M_(w), of from about 60,000 to about200,000 including narrower ranges within this range and the numberswithin this range. For example, in further embodiments of the invention,the polyethylene composition has a weight average molecular weight,M_(w), of from about 65,000 to 175,000, or from about 65,000 to about150,000, or from about 65,000 to about 140,000.

In an embodiment of the invention, the polyethylene composition has az-average molecular weight, M_(z), of less than 450,000.

In embodiments of the invention, the polyethylene composition has az-average molecular weight, M_(z) of from 250,000 to 450,000 includingnarrower ranges within this range and the numbers within this range. Forexample, in further embodiments of the invention, the polyethylenecomposition has a z-average molecular weight, M_(w), of from 250,000 to425,000, or from 275,000 to 425,000, or from 250,000 to below 450,000,or from 250,000 to 410,000.

In embodiments of the present invention, the polyethylene compositionhas a molecular weight distribution Mw/Mn of from 3 to 11 or a narrowerrange within this range. For example, in further embodiments of theinvention, the polyethylene composition has a M_(w)/M_(n) of from 4.0 to10.0, or from 4.0 to 9.0 or from 5.0 to 10.0, or from 5.0 to 9.0, orfrom 4.5 to 10.0, or from 4.5 to 9.5, or from 4.5 to 9.0, or from 4.5 to8.5, or from 5.0 to 8.5.

In embodiments of the present invention, the polyethylene compositionhas a molecular weight distribution Mw/Mn of from 6 to 13 or a narrowerrange within this range. For example, in further embodiments of theinvention, the polyethylene composition has a M_(w)/M_(n) of from 7.0 to12.0, or from 8.0 to 12.0, or from 8.5 to 12.0, or from 9.0 to 12.0, orfrom 9.0, to 12.5 or from 8.5 to 12.5.

In embodiments of the invention, the polyethylene composition has aratio of Z-average molecular weight to weight average molecular weight(M_(z)/M_(w)) of from 2.0 to 5.0, or from 2.25 to 4.75, or from 2.25 to4.5, or from 2.5 to 4.25, or from 2.75 to 4.0, or from 2.75 to 3.75, orbetween 3.0 and 4.0.

In embodiments of the invention, the polyethylene composition has aratio of Z-average molecular weight to weight average molecular weight(M_(z)/M_(w)) of less than 5.0, or less than 4.5, or less than 4.0, orless than 3.5.

In an embodiment of the invention, the polyethylene composition has abroadness factor defined as (M_(w)/M_(n))/(M_(z)/M_(w)) of at least2.70, or at least 2.75, or at least 2.8, or at least 2.85, or at least2.90, or at least 2.95, or at least 3.00, or at least 3.05.

In embodiments of the invention, the polyethylene composition has a meltflow ratio defined as I₂₁/I₂ of >40, or ≧45, or ≧50, or ≧60, or ≧65. Ina further embodiment of the invention, the polyethylene composition hasa melt flow ratio I₂₁/I₂ of from about 40 to about 100, and includingnarrower ranges within this range. For example, the polyethylenecomposition may have a melt flow ratio I₂₁/I₂ of from about 45 to about90, or from about 45 to about 80, or from about 45 to about 75, or fromabout 45 to about 70, or from about 50 to about 90, or from about 50 toabout 80, or from about 50 to about 75, or from about 50 to about 70.

In an embodiment of the invention, the polyethylene composition has amelt flow rate defined as I₂₁/I₅ of less than 30. In another embodimentof the invention, the polyethylene composition has a melt flow ratedefined as I₂₁/I₅ of less than 25. In another embodiment of theinvention, the polyethylene composition has a melt flow rate defined asI₂₁/I₅ of less than 20.

In an embodiment of the invention, the polyethylene composition has ashear viscosity at about 10⁵ s⁻¹ (240° C.) of less than about 10 (Pa·s).In further embodiments of the invention, the polyethylene compositionhas a shear viscosity at about 10⁵ s⁻¹ (240° C.) of less than 7.5 Pa·s,or less than 6.0 Pa·s.

In an embodiment of the invention, the polyethylene composition has ahexane extractables level of below 0.55 wt %.

In an embodiment of the invention, the polyethylene composition has atleast one type of alpha-olefin that has at least 4 carbon atoms and itscontent is less than 0.75 mol % as determined by ¹³C NMR. In anembodiment of the invention, the polyethylene composition has at leastone type of alpha-olefin that has at least 4 carbon atoms and itscontent is less than 0.65 mol % as determined by ¹³C NMR. In anembodiment of the invention, the polyethylene composition has at leastone type of alpha-olefin that has at least 4 carbon atoms and itscontent is less than 0.55 mol % as determined by ¹³C NMR.

In an embodiment of the invention, the shear viscosity ratio,SVR_((10,1000)) at 240° C. of the polyethylene composition can be fromabout 4.0 to 25, or from 4.0 to 20, or from 4.0 to 17. The shearviscosity ratio SVR_((10,1000)) is determined by taking the ratio ofshear viscosity at shear rate of 10 s⁻¹ and shear viscosity at shearrate of 1000 s⁻¹ as measured with a capillary rheometer at constanttemperature (e.g. 240° C.), and a die with L/D ratio of 20 and diameterof 0.06″. Without wishing to be bound by theory, the higher the valuefor the shear viscosity ratio, the easier the polyethylene compositionis to be processed on a converting equipment for caps and closures.

In embodiments of the invention, the polyethylene composition has ashear viscosity ratio (η₁₀/η₁₀₀₀ at 240° C.) of ≦12.0, ≦12.5, or ≧13.0,or ≧13.5, or ≧14.0, or ≧14.5, or ≧15.0, or ≧17.5, or ≧20.0. The “shearviscosity ratio” is used herein as a means to describe the relativeprocessability of a polyethylene composition.

In further embodiments of the invention, the shear viscosity ratio,SVR_((10,1000)) at 240° C. of the polyethylene composition is from 10.0to 30, or from 12.0 to 30, or from 12.0 to 27.5, or from 12.0 to 25, orfrom 12.5 to 30, or from 12.5 to 27.5, or from 12.5 to 25.

In an embodiment of the invention, the shear thinning index,SHI_((1,100)) of the polyethylene composition is less than about 10; inanother embodiment the SHI_((1,100)) will be less than about 7. Theshear thinning index (SHI), was calculated using dynamic mechanicalanalysis (DMA) frequency sweep methods as disclosed in PCT applicationsWO 2006/048253 and WO 2006/048254. The SHI value is obtained bycalculating the complex viscosities η*(1) and η* (100) at a constantshear stress of 1 kPa (G*) and 100 kPa (G*), respectively.

In an embodiment of the invention, the SHI_((1,100)) of the polyethylenecomposition satisfies the equation: SHI_((1,100))<−10.58 (log I₁ ofpolyethylene composition in g/10 min)/(g/10 min)+12.94. In anotherembodiment of the invention, the SHI_((1,100)) of the polyethylenecomposition satisfies the equation:

SHI_((1,100))<−5.5(log I ₂ of the polyethylene composition in g/10min)/(g/10 min)+9.66.

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of atleast 20 hours, or at least 60 hours, or at least 80 hours, or at least120 hours, or at least 150 hours, or from 60 to 400 hours, or from 100to 250 hours, or from 60 to 250 hours as measured according to ASTMD1693 (at 10% Igepal and 50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of atleast 200 hours, as measured according to ASTM D1693 (at 10% Igepal and50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of atleast 250 hours, as measured according to ASTM D1693 (at 10% Igepal and50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of atleast 300 hours, as measured according to ASTM D1693 (at 10% Igepal and50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of atleast 350 hours, as measured according to ASTM D1693 (at 10% Igepal and50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of atleast 400 hours, as measured according to ASTM D1693 (at 10% Igepal and50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of atleast 500 hours, as measured according to ASTM D1693 (at 10% Igepal and50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of from200 to 1500 hours, as measured according to ASTM D1693 (at 10% Igepaland 50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of from200 to 1250 hours, as measured according to ASTM D1693 (at 10% Igepaland 50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition, hasan environment stress crack resistance ESCR Condition B at 10% of from300 to 1500 hours, as measured according to ASTM D1693 (at 10% Igepaland 50° C. under condition B).

In an embodiment of the invention, the polyethylene composition or amolded article (or plaque) made from the polyethylene composition has anotched Izod impact strength of at least 60 J/m, or at least 70 J/m, orat least 80 J/m, or at least 90 J/m, or at least 100 J/m as measuredaccording to ASTM D256.

In an embodiment of the invention the polyethylene composition of thecurrent invention has a density of from 0.949 to 0.956 g/cm³; a meltindex, I₂, of from 0.5 to 3.0 g/10 min; a molecular weight distributionof from 4.0 to 10.0; a number average molecular weight, M_(n), of below30,000; a shear viscosity at 10⁵ s⁻¹ (240° C.) of less than 10 (Pa·s), ahexane extractables of less than 0.55%, a notched Izod impact strengthof more than 60 J/m, and an ESCR B at 10% of at least 20 hours.

In an embodiment of the invention the polyethylene composition of thecurrent invention has a density of from 0.949 to 0.956 g/cm³; a meltindex, I₂, of from 0.5 to 3.0 g/10 min; a molecular weight distributionof from 4.5 to 9.5; a number average molecular weight, M_(n), of below30,000; a shear viscosity at 10⁵ s⁻¹ (240° C.) of less than 7 (Pa·s), ahexane extractables of less than 0.55%, a notched Izod impact strengthof more than 60 J/m and an ESCR B at 10% of at least 80 hours.

In an embodiment of the invention the polyethylene composition of thecurrent invention has a density of from 0.949 to 0.956 g/cm³; a meltindex, I₂, of from 0.2 to 3.0 g/10 min; a molecular weight distributionof from 6.0 to 13.0; a number average molecular weight, M_(n), of below30,000; a shear viscosity at 10⁵ s⁻¹ (240° C.) of less than 10 (Pa·s), ahexane extractables of less than 0.55%, a notched Izod impact strengthof more than 60 J/m, and an ESCR B at 10% of at least 200 hours.

In embodiments of the invention, the polyethylene composition has a 2%secant flexural modulus in megapascals (MPa) of greater than about 750,or greater than about 850, or greater than about 1000, or from about 750to about 1600, or from about 750 to about 1250, or from about 850 toabout 1150. In some embodiments the polyethylene composition furthercomprises a nucleating agent which increases the 2% secant flexuralmodulus in megapascals (MPa) to above these ranges to for example frommore than about 1000 and up to about 1600. Without wishing to be boundby theory, the 2% secant flexural modulus is a measure of polymerstiffness. The higher the 2% secant flexural modulus, the higher thepolymer stiffness.

In an embodiment of the invention the polyethylene composition of thecurrent invention has a density of from 0.949 to 0.956 g/cm³; a meltindex, I₂, of from 0.2 to 3.0 g/10 min; a molecular weight distributionof from 7.0 to 12.0; a number average molecular weight, M_(n), of below30,000; a shear viscosity at 10⁵ s⁻¹ (240° C.) of less than 7 (Pa·s), ahexane extractables of less than 0.55%, a notched Izod impact strengthof more than 60 J/m and an ESCR B at 10% of at least 200 hours.

In an embodiment of the invention, the polyethylene composition has astress exponent, defined as Log₁₀[I₆/I₂]/Log₁₀[6.48/2.16], which is≦1.50. In further embodiments of the invention the polyethylenecomposition has a stress exponent, Log₁₀[I₆/I₂]/Log₁₀[6.48/2.16] of lessthan 1.50, or less than 1.48, or less than 1.45, or less than 1.43, orless than 1.40.

In an embodiment of the invention, the polyethylene composition has acomposition distribution breadth index (CDBI₅₀), as determined bytemperature elution fractionation (TREF), of 60 weight %. In furtherembodiments of the invention, the polyethylene composition will have aCDBI₅₀ of greater than 65 weight %, or greater than 70 weight %, orgreater than 75 weight %, or greater than 80 weight %.

In an embodiment of the invention, the polyethylene composition has acomposition distribution breadth index (CDBI₂₅), as determined bytemperature elution fractionation (TREF), of ≧50 weight %. In furtherembodiments of the invention, the polyethylene composition will have aCDBI₂₅ of greater than 55 weight %, or greater than 60 weight %, orgreater than 65 weight %, or greater than 70 weight %.

The polyethylene composition of this invention can be made using anyconventional blending method such as but not limited to physicalblending and in-situ blending by polymerization in multi reactorsystems. For example, it is possible to perform the mixing of the firstethylene copolymer with the second ethylene copolymer by molten mixingof the two preformed polymers. Preferred are processes in which thefirst and second ethylene copolymers are prepared in at least twosequential polymerization stages, however, both in-series andin-parallel reactor process are contemplated for use in the currentinvention. If the at least two reactors are configured in parallel,comonomer addition to each reactor makes an ethylene copolymer in eachreactor. If the at least two reactors are configured in series,comonomer may be added to at least the first reactor, and unreactedcomonomer can flow into later reactors to make an ethylene copolymer ineach reactor. Alternatively, if the at least two reactors are configuredin series, comonomer may be added to each reactor, to make an ethylenecopolymer in each reactor. Gas phase, slurry phase or solution phasereactor systems may be used, with solution phase reactor systems beingpreferred.

In an embodiment of the current invention, a dual reactor solutionprocess is used as has been described in for example U.S. Pat. No.6,372,864 and U.S. Patent Publication Application No. 20060247373A1which are incorporated herein by reference.

Homogeneously branched ethylene copolymers can be prepared using anycatalyst capable of producing homogeneous branching. Generally, thecatalysts will be based on a group 4 metal having at least onecyclopentadienyl ligand that is well known in the art. Examples of suchcatalysts which include metallocenes, constrained geometry catalysts andphosphinimine catalysts are typically used in combination withactivators selected from methylaluminoxanes, boranes or ionic boratesalts and are further described in U.S. Pat. Nos. 3,645,992; 5,324,800;5,064,802; 5,055,438; 6,689,847; 6,114,481 and 6,063,879, Such catalystsmay also be referred to as “single site catalysts” to distinguish themfrom traditional Ziegler-Natta or Phillips catalysts which are also wellknown in the art. In general, single site catalysts produce ethylenecopolymers having a molecular weight distribution (M_(w)/M_(n)) of lessthan about 3.0 and a composition distribution breadth index (CDBI₅₀) ofgreater than about 50% by weight.

In an embodiment of the current invention, homogeneously branchedethylene polymers are prepared using an organometallic complex of agroup 3, 4 or 5 metal that is further characterized as having aphosphinimine ligand. Such catalysts are known generally asphosphinimine catalysts. Some non-limiting examples of phosphiniminecatalysts can be found in U.S. Pat. Nos. 6,342,463; 6,235,672;6,372,864; 6,984,695; 6,063,879; 6,777,509 and 6,277,931 all of whichare incorporated by reference herein.

Some non-limiting examples of metallocene catalysts can be found in U.S.Pat. Nos. 4,808,561; 4,701,432; 4,937,301; 5,324,800; 5,633,394;4,935,397; 6,002,033 and 6,489,413, which are incorporated herein byreference. Some non-limiting examples of constrained geometry catalystscan be found in U.S. Pat. Nos. 5,057,475; 5,096,867; 5,064,802;5,132,380; 5,703,187 and 6,034,021, all of which are incorporated byreference herein in their entirety.

In an embodiment of the invention, use of a single site catalyst thatdoes not produce long chain branching (LCB) is preferred. Withoutwishing to be bound by any single theory, long chain branching canincrease viscosity at low shear rates, thereby negatively impactingcycle times during the manufacture of caps and closures, such as duringthe process of compression molding. Long chain branching may bedetermined using ¹³C NMR methods and may be quantitatively assessedusing the method disclosed by Randall in Rev. Macromol. Chem. Phys. C29(2 and 3), p. 285.

In an embodiment of the invention, the polyethylene composition willcontain fewer than 0.3 long chain branches per 1000 carbon atoms. Inanother embodiment of the invention, the polyethylene composition willcontain fewer than 0.01 long chain branches per 1000 carbon atoms.

In an embodiment of the invention, the polyethylene composition (definedas above) is prepared by contacting ethylene and at least onealpha-olefin with a polymerization catalyst under solution phasepolymerization conditions in at least two polymerization reactors (foran example of solution phase polymerization conditions see, for example,U.S. Pat. Nos. 6,372,864; 6,984,695 and U.S. Patent PublicationApplication No. 2006/0247373A1 which are incorporated herein byreference).

In an embodiment of the invention, the polyethylene composition isprepared by contacting at least one single site polymerization catalystsystem (comprising at least one single site catalyst and at least oneactivator) with ethylene and a least one comonomer (e.g., a C3-C8alpha-olefin) under solution polymerization conditions in at least twopolymerization reactors.

In an embodiment of the invention, a group 4 single site catalystsystem, comprising a single site catalyst and an activator, is used in asolution phase dual reactor system to prepare a bimodal polyethylenecomposition by polymerization of ethylene in the presence of analpha-olefin comonomer.

In an embodiment of the invention, a group 4 single site catalystsystem, comprising a single site catalyst and an activator, is used in asolution phase dual reactor system to prepare a bimodal polyethylenecomposition by polymerization of ethylene in the presence of 1-octene.

In an embodiment of the invention, a group 4 phosphinimine catalystsystem, comprising a phosphinimine catalyst and an activator, is used ina solution phase dual reactor system to prepare a bimodal polyethylenecomposition by polymerization of ethylene in the presence of analpha-olefin comonomer.

In an embodiment of the invention, a group 4 phosphinimine catalystsystem, comprising a phosphinimine catalyst and an activator, is used ina solution phase dual reactor system to prepare a bimodal polyethylenecomposition by polymerization of ethylene in the presence of 1-octene.

In an embodiment of the invention, a solution phase dual reactor systemcomprises two solution phase reactors connected in series.

In an embodiment of the invention, a polymerization process to preparethe polyethylene composition comprises contacting at least one singlesite polymerization catalyst system with ethylene and at least onealpha-olefin comonomer under solution polymerization conditions in atleast two polymerization reactors.

In an embodiment of the invention, a polymerization process to preparethe polyethylene composition comprises contacting at least one singlesite polymerization catalyst system with ethylene and at least onealpha-olefin comonomer under solution polymerization conditions in atleast a first reactor and a second reactor configured in series.

In an embodiment of the invention, a polymerization process to preparethe polyethylene composition comprises contacting at least one singlesite polymerization catalyst system with ethylene and at least onealpha-olefin comonomer under solution polymerization conditions in atleast a first reactor and a second reactor configured in series, withthe at least one alpha-olefin comonomer being fed exclusively to thefirst reactor.

The production of the polyethylene composition of the present inventionwill typically include an extrusion or compounding step. Such steps arewell known in the art.

The polyethylene composition can comprise further polymer components inaddition to the first and second ethylene polymers. Such polymercomponents include polymers made in situ or polymers added to thepolymer composition during an extrusion or compounding step.

Optionally, additives can be added to the polyethylene composition.Additives can be added to the polyethylene composition during anextrusion or compounding step, but other suitable known methods will beapparent to a person skilled in the art. The additives can be added asis or as part of a separate polymer component (i.e., not the first orsecond ethylene polymers described above) added during an extrusion orcompounding step. Suitable additives are known in the art and includebut are not-limited to antioxidants, phosphites and phosphonites,nitrones, antacids, UV light stabilizers, UV absorbers, metaldeactivators, dyes, fillers and reinforcing agents, nano-scale organicor inorganic materials, antistatic agents, lubricating agents such ascalcium stearates, slip additives such as erucimide, and nucleatingagents (including nucleators, pigments or any other chemicals which mayprovide a nucleating effect to the polyethylene composition). Theadditives that can be optionally added are typically added in amount ofup to 20 weight percent (wt %).

One or more nucleating agent(s) may be introduced into the polyethylenecomposition by kneading a mixture of the polymer, usually in powder orpellet form, with the nucleating agent, which may be utilized alone orin the form of a concentrate containing further additives such asstabilizers, pigments, antistatics, UV stabilizers and fillers. Itshould be a material which is wetted or absorbed by the polymer, whichis insoluble in the polymer and of melting point higher than that of thepolymer, and it should be homogeneously dispersible in the polymer meltin as fine a form as possible (1 to 10 μm). Compounds known to have anucleating capacity for polyolefins include salts of aliphatic monobasicor dibasic acids or arylalkyl acids, such as sodium succinate oraluminum phenylacetate; and alkali metal or aluminum salts of aromaticor alicyclic carboxylic acids such as sodium β-naphthoate. Anothercompound known to have nucleating capacity is sodium benzoate. Theeffectiveness of nucleation may be monitored microscopically byobservation of the degree of reduction in size of the spherulites intowhich the crystallites are aggregated.

Examples of nucleating agents which are commercially available and whichmay be added to the polyethylene composition are dibenzylidene sorbitalesters (such as the products sold under the trademark Millad™ 3988 byMilliken Chemical and Irgacleamm by Ciba Specialty Chemicals). Furtherexamples of nucleating agents which may added to the polyethylenecomposition include the cyclic organic structures disclosed in U.S. Pat.No. 5,981,636 (and salts thereof, such as disodium bicyclo[2.2.1]heptenedicarboxylate); the saturated versions of the structures disclosed inU.S. Pat. No. 5,981,636 (as disclosed in U.S. Pat. No. 6,465,551; Zhaoet al., to Milliken); the salts of certain cyclic dicarboxylic acidshaving a hexahydrophtalic acid structure (or “HHPA” structure) asdisclosed in U.S. Pat. No. 6,599,971 (Dotson et al., to Milliken); andphosphate esters, such as those disclosed in U.S. Pat. No. 5,342,868 andthose sold under the trade names NA-11 and NA-21 by Asahi Denka Kogyo,cylic dicarboxylates and the salts thereof, such as the divalent metalor metalloid salts, (particularly, calcium salts) of the HHPA structuresdisclosed in U.S. Pat. No. 6,599,971. For clarity, the HHPA structuregenerally comprises a ring structure with six carbon atoms in the ringand two carboxylic acid groups which are substituents on adjacent atomsof the ring structure. The other four carbon atoms in the ring may besubstituted, as disclosed in U.S. Pat. No. 6,599,971. An example is1,2-cyclohexanedicarboxylicacid, calcium salt (CAS registry number491589-22-1). Still further examples of nucleating agents which mayadded to the polyethylene composition include those disclosed inWO2015042561, WO2015042563, WO2015042562 and WO 2011050042.

Many of the above described nucleating agents may be difficult to mixwith the polyethylene composition that is being nucleated and it isknown to use dispersion aids, such as for example, zinc stearate, tomitigate this problem.

In an embodiment of the invention, the nucleating agents are welldispersed in the polyethylene composition.

In an embodiment of the invention, the amount of nucleating agent usedis comparatively small (from 100 to 3000 parts by million per weight(based on the weight of the polyethylene composition)) so it will beappreciated by those skilled in the art that some care must be taken toensure that the nucleating agent is well dispersed. In an embodiment ofthe invention, the nucleating agent is added in finely divided form(less than 50 microns, especially less than 10 microns) to thepolyethylene composition to facilitate mixing. This type of “physicalblend” (i.e., a mixture of the nucleating agent and the resin in solidform) is generally preferable to the use of a “masterbatch” of thenucleator (where the term “masterbatch” refers to the practice of firstmelt mixing the additive—the nucleator, in this case—with a small amountof the polyethylene composition resin—then melt mixing the “masterbatch”with the remaining bulk of the polyethylene composition resin).

In an embodiment of the invention, an additive such as nucleating agentmay be added to the polyethylene composition by way of a “masterbatch”,where the term “masterbatch” refers to the practice of first melt mixingthe additive (e.g., a nucleator) with a small amount of the polyethylenecomposition, followed by melt mixing the “masterbatch” with theremaining bulk of the polyethylene composition.

In an embodiment of the invention, the polymer composition furthercomprises a nucleating agent or a mixture of nucleating agents.

In an embodiment of the invention, the polymer compositions describedabove are used in the formation of molded articles. For example,articles formed by compression molding and injection molding arecontemplated. Such articles include, for example, caps, screw caps, andclosures for bottles. However, a person skilled in the art will readilyappreciate that the compositions described above may also be used forother applications such as, but not limited to, film, injection blowmolding, blow molding and sheet extrusion applications.

In an embodiment of the invention, the polyethylene compositionsdescribed above are used in the formation of a closure for bottles,containers, pouches and the like. For example, closures for bottlesformed by compression molding or injection molding are contemplated.Such closures include, for example, hinged caps, hinged screw caps,hinged snap-top caps, and hinged closures for bottles, containers,pouches and the like.

In an embodiment of the invention, a closure (or cap) is a screw cap fora bottle, container, pouches and the like.

In an embodiment of the invention, a closure (or cap) is a snap closurefor a bottle, container, pouches and the like.

In an embodiment of the invention, a closure (or cap) comprises a hingemade of the same material as the rest of the closure (or cap).

In an embodiment of the invention, a closure (or cap) is hinged closure.

In an embodiment of the invention, a closure (or cap) is a hingedclosure for bottles, containers, pouches and the like.

In an embodiment of the invention, a closure (or cap) is a flip-tophinge closure, such as a flip-top hinge closure for use on a plasticketchup bottle or similar containers containing foodstuffs.

When a closure is a hinged closure, it comprises a hinged component andgenerally consists of at least two bodies which are connected by athinner section that acts as a hinge allowing the at least two bodies tobend from an initially molded position. The thinner section may becontinuous or web-like, wide or narrow.

A useful closure (for bottles, containers and the like) is a hingedclosure and may consist of two bodies joined to each other by at leastone thinner bendable portion (e.g., the two bodies can be joined by asingle bridging portion, or more than one bridging portion, or by awebbed portion, etc.). A first body may contain a dispensing hole andwhich may snap onto or screw onto a container to cover a containeropening (e.g., a bottle opening) while a second body may serve as a snapon lid which may mate with the first body.

The caps and closures, of which hinged caps and closures and screw capsare a subset, can be made according to any known method, including, forexample, injection molding and compression molding techniques that arewell known to persons skilled in the art. Hence, in an embodiment of theinvention a closure (or cap) comprising the polyethylene composition(defined above) is prepared with a process comprising at least onecompression molding step and/or at least one injection molding step.

In one embodiment, the caps and closures (including single piece ormulti-piece variants and hinged variants) comprise the polyethylenecomposition described above and have good organoleptic properties, goodtoughness, as well as good ESCR values. Hence, the closures and caps ofthis embodiment are well suited for sealing bottles, containers and thelike, for example, bottles that may contain drinkable water, and otherfoodstuffs, including but not limited to liquids that are under anappropriate pressure (i.e., carbonated beverages or appropriatelypressurized drinkable liquids).

The closures and caps may also be used for sealing bottles containingdrinkable water or non-carbonated beverages (e.g., juice). Otherapplications, include caps and closures for bottles, containers andpouches containing foodstuffs, such as, for example, ketchup bottles andthe like.

The invention is further illustrated by the following non-limitingexamples.

Examples

M_(n), M_(w), and M_(z) (g/mol) were determined by high temperature GelPermeation Chromatography (GPC) with differential refractive index (DRI)detection using universal calibration (e.g., ASTM-D6474-99). GPC datawas obtained using an instrument sold under the trade name “Waters150c”, with 1,2,4-trichlorobenzene as the mobile phase at 140° C. Thesamples were prepared by dissolving the polymer in this solvent and wererun without filtration. Molecular weights are expressed as polyethyleneequivalents with a relative standard deviation of 2.9% for the numberaverage molecular weight (“Mn”) and 5.0% for the weight averagemolecular weight (“Mw”). The molecular weight distribution (MWD) is theweight average molecular weight divided by the number average molecularweight, M_(w)/M_(n). The z-average molecular weight distribution isM_(z)/M_(n). Polymer sample solutions (1 to 2 mg/mL) were prepared byheating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating on awheel for 4 hours at 150° C. in an oven. The antioxidant2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture in orderto stabilize the polymer against oxidative degradation. The BHTconcentration was 250 ppm. Sample solutions were chromatographed at 140°C. on a PL 220 high-temperature chromatography unit equipped with fourShodex columns (HT803, HT804, HT805 and HT806) using TCB as the mobilephase with a flow rate of 1.0 mL/minute, with a differential refractiveindex (DRI) as the concentration detector. BHT was added to the mobilephase at a concentration of 250 ppm to protect the columns fromoxidative degradation. The sample injection volume was 200 mL. The rawdata were processed with Cirrus GPC software. The columns werecalibrated with narrow distribution polystyrene standards. Thepolystyrene molecular weights were converted to polyethylene molecularweights using the Mark-Houwink equation, as described in the ASTMstandard test method D6474.

Primary melting peak (° C.), heat of fusion (J/g) and crystallinity (%)was determined using differential scanning calorimetry (DSC) as follows:the instrument was first calibrated with indium; after the calibration,a polymer specimen is equilibrated at 0° C. and then the temperature wasincreased to 200° C. at a heating rate of 10° C./min; the melt was thenkept isothermally at 200° C. for five minutes; the melt was then cooledto 0° C. at a cooling rate of 10° C./min and kept at 0° C. for fiveminutes; the specimen was then heated to 200° C. at a heating rate of10° C./min. The DSC Tm, heat of fusion and crystallinity are reportedfrom the 2^(nd) heating cycle.

The short chain branch frequency (SCB per 1000 carbon atoms) ofcopolymer samples was determined by Fourier Transform InfraredSpectroscopy (FTIR) as per the ASTM D6645-01 method. A Thermo-Nicolet750 Magna-IR Spectrophotometer equipped with OMNIC version 7.2a softwarewas used for the measurements.

Comonomer content can also be measured using ¹³C NMR techniques asdiscussed in Randall, Rev. Macromol. Chem. Phys., C29 (2&3), p. 285;U.S. Pat. No. 5,292,845 and WO 2005/121239.

Polyethylene composition density (g/cm³) was measured according to ASTMD792.

Hexane extractables were determined according to ASTM D5227.

Shear viscosity was measured by using a Kayeness WinKARS CapillaryRheometer (model # D5052M-115). For the shear viscosity at lower shearrates, a die having a die diameter of 0.06 inch and L/D ratio of 20 andan entrance angle of 180 degrees was used. For the shear viscosity athigher shear rates, a die having a die diameter of 0.012 inch and L/Dratio of 20 was used.

The Shear viscosity ratio as the term is used in the present inventionis defined as: η₁₀/η₁₀₀₀ at 240° C. The η₁₀ is the melt shear viscosityat the shear rate of 10 s⁻¹ and the η₁₀₀₀ is the melt shear viscosity atthe shear rate of 1000 s⁻¹ measured at 240° C.

Melt indexes, I₂, I₅, I₆ and I₂₁ for the polyethylene composition weremeasured according to ASTM D1238 (when conducted at 190° C., using a2.16 kg, a 5 kg, a 6.48 kg and a 21 kg weight, respectively).

To determine CDBI₅₀, a solubility distribution curve is first generatedfor the polyethylene composition. This is accomplished using dataacquired from the TREF technique. This solubility distribution curve isa plot of the weight fraction of the copolymer that is solubilized as afunction of temperature. This is converted to a cumulative distributioncurve of weight fraction versus comonomer content, from which the CDBI₅₀is determined by establishing the weight percentage of a copolymersample that has a comonomer content within 50% of the median comonomercontent on each side of the median (See WO 93/03093 and U.S. Pat. No.5,376,439). The CDBI₂₅ is determined by establishing the weightpercentage of a copolymer sample that has a comonomer content within 25%of the median comonomer content on each side of the median.

The specific temperature rising elution fractionation (TREF) method usedherein was as follows. Polymer samples (50 to 150 mg) were introducedinto the reactor vessel of a crystallization-TREF unit (Polymer ChAR™).The reactor vessel was filled with 20 to 40 ml 1,2,4-trichlorobenzene(TCB), and heated to the desired dissolution temperature (e.g., 150° C.)for 1 to 3 hours. The solution (0.5 to 1.5 ml) was then loaded into theTREF column filled with stainless steel beads. After equilibration at agiven stabilization temperature (e.g., 110° C.) for 30 to 45 minutes,the polymer solution was allowed to crystallize with a temperature dropfrom the stabilization temperature to 30° C. (0.1 or 0.2° C./minute).After equilibrating at 30° C. for 30 minutes, the crystallized samplewas eluted with TCB (0.5 or 0.75 mL/minute) with a temperature ramp from30° C. to the stabilization temperature (0.25 or 1.0° C./minute). TheTREF column was cleaned at the end of the run for 30 minutes at thedissolution temperature. The data were processed using Polymer ChARsoftware, Excel spreadsheet and TREF software developed in-house.

The melt index, I₂ and density of the first and second ethylenecopolymers were estimated by GPC and GPC-FTIR deconvolutions asdiscussed further below.

High temperature GPC equipped with an online FTIR detector (GPC-FTIR)was used to measure the comonomer content as the function of molecularweight. Mathematical deconvolutions are performed to determine therelative amount of polymer, molecular weight and comonomer content ofthe component made in each reactor, by assuming that each polymercomponent follows a Flory's molecular weight distribution function andit has a homogeneous comonomer distribution across the whole molecularweight range.

For these single site catalyzed resins, the GPC data from GPCchromatographs was fit based on Flory's molecular weight distributionfunction.

To improve the deconvolution accuracy and consistency, as a constraint,the melt index, I₂, of the targeted resin was set and the followingrelationship was satisfied during the deconvolution:

Log₁₀(I ₂)=22.326528+0.003467*[Log₁₀(M _(n))]³−4.322582*Log₁₀(M_(w))−0.180061*[Log₁₀(M _(z))]²+0.026478*[Log₁₀(M _(z))]³

where the experimentally measured overall melt index, I₂, was used onthe left side of the equation, while M_(n) of each component(M_(w)=2×M_(n) and M_(z)=1.5×M_(w) for each component) was adjusted tochange the calculated overall M_(n), M_(w) and M_(z) of the compositionuntil the fitting criteria were met. During the deconvolution, theoverall M_(n), M_(w) and M_(z) are calculated with the followingrelationships: M_(n)=1/Sum(w_(i)/M_(n)(i)), M_(w)=Sum(w_(i)×M_(w)(i)),M_(z)=Sum(w_(i)×M_(z)(i)²), where i represents the i-th component andw_(i) represents the relative weight fraction of the i-th component inthe composition.

The uniform comonomer distribution (which results from the use of asingle site catalyst) of the resin components (i.e., the first andsecond ethylene copolymers) allowed the estimation of the short chainbranching content (SCB) from the GPC-FTIR data, in branches per 1000carbon atoms and calculation of comonomer content (in mol %) and density(in g/cm³) for the first and second ethylene copolymers, based on thedeconvoluted relative amounts of first and second ethylene copolymercomponents in the polyethylene composition, and their estimated resinmolecular weight parameters from the above procedure.

A component (or composition) density model and a component (orcomposition) melt index, I₂, model was used according to the followingequations to calculate the density and melt index I₂ of the first andsecond ethylene polymers:

density=0.979863−0.00594808*(FTIR SCB/1000C)^(0.65)−0.000383133*[Log₁₀(M_(n))]³0.00000577986*(M _(w) /M _(n))3+0.00557395*(M _(z) /M_(w))^(0.25);

Log₁₀(melt index,I ₂)=22.326528+0.003467*[Log₁₀(M_(n))]³−4.322582*Log₁₀(M _(w))−0.180061*[Log₁₀(M_(z))]²+0.026478*[Log₁₀(M _(z))]³

where the M_(n), M_(w) and M_(z) were the deconvoluted values of theindividual ethylene polymer components, as obtained from the results ofthe above GPC deconvolutions. Hence, these two models were used toestimate the melt indexes and the densities of the components (i.e., thefirst and second ethylene copolymers).

Plaques molded from the polyethylene compositions were tested accordingto the following ASTM methods: Bent Strip Environmental Stress CrackResistance (ESCR) at Condition B at 10% IGEPAL at 50° C., ASTM D1693;notched Izod impact properties, ASTM D256; Flexural Properties, ASTM D790; Tensile properties, ASTM D 638; Vicat softening point, ASTM D 1525;Heat deflection temperature, ASTM D 648.

Dynamic mechanical analyses were carried out with a rheometer, namelyRheometrics Dynamic Spectrometer (RDS-II) or Rheometrics SR5 or ATSStresstech, on compression molded samples under nitrogen atmosphere at190° C., using 25 mm diameter cone and plate geometry. The oscillatoryshear experiments were done within the linear viscoelastic range ofstrain (10% strain) at frequencies from 0.05 to 100 rad/s. The values ofstorage modulus (G′), loss modulus (G″), complex modulus (G*) andcomplex viscosity (η*) were obtained as a function of frequency. Thesame rheological data can also be obtained by using a 25 mm diameterparallel plate geometry at 190° C. under nitrogen atmosphere. TheSHI(1,100) value is calculated according to the methods described in WO2006/048253 and WO 2006/048254.

Examples of the polyethylene compositions were produced in a dualreactor solution polymerization process in which the contents of thefirst reactor flow into the second reactor. This in-series “dualreactor” process produces an “in-situ” polyethylene blend (i.e., thepolyethylene composition). Note, that when an in-series reactorconfiguration is used, un-reacted ethylene monomer, and un-reactedalpha-olefin comonomer present in the first reactor will flow into thedownstream second reactor for further polymerization.

In the present inventive examples, although no co-monomer is feddirectly to the downstream second reactor, an ethylene copolymer isnevertheless formed in the second reactor due to the significantpresence of un-reacted 1-octene flowing from the first reactor to thesecond reactor where it is copolymerized with ethylene. Each reactor issufficiently agitated to give conditions in which components are wellmixed. The volume of the first reactor was 12 liters and the volume ofthe second reactor was 22 liters. Optionally, a tubular reactor sectionwhich receives the discharge from the second reactor may be also bepresent as described in U.S. Pat. No. 8,101,693. These are the pilotplant scales. The first reactor was operated at a pressure of 10500 to35000 kPa and the second reactor was operated at a lower pressure tofacilitate continuous flow from the first reactor to the second. Thesolvent employed was methylpentane. The process operates usingcontinuous feed streams. The catalyst employed in the dual reactorsolution process experiments was a titanium complex having aphosphinimine ligand, a cyclopentadienide ligand and two activatableligands, such as but not limited to chloride ligands. A boron basedco-catalyst was used in approximately stoichiometric amounts relative tothe titanium complex. Commercially available methylaluminoxane (MAO) wasincluded as a scavenger at an Al:Ti of about 40:1. In addition,2,6-di-tert-butylhydroxy-4-ethylbenzene was added to scavenge freetrimethylaluminum within the MAO in a ratio of Al:OH of about 0.5:1.

The polymerization conditions used to make the inventive compositionsare provided in Table 1.

Inventive and comparative polyethylene composition properties aredescribed in Tables 2.

Calculated properties for the first ethylene copolymer and the secondethylene copolymer for selected comparative and inventive polyethylenecompositions, as obtained from GPC-FTIR deconvolution studies, areprovided in Table 3.

The properties of pressed plaques made from comparative and inventivepolyethylene compositions are provided in Table 4.

Comparative polyethylene compositions (Comparative Examples 1-5) aremade using a single site phosphinimine catalyst in a dual reactorsolution process and have an ESCR at condition B10 of less than 24 hoursand a SCB1/SCB2 ratio of 0.50 or less.

Comparative polyethylene composition 6 (Comparative Example 6) is acommercially available, high density, bimodal polyethylene resin fromDow Chemical, DMDA-1250 NT 7 which has an ESCR at condition B10 (at 50°C., 10% IGEPAL) of less than 200 hours, and an Mz of greater than500,000.

Comparative polyethylene composition 7 (Comparative Example 7) is acommercially available, high density polyethylene resin from DowChemical, DMDA-1270 NT 7 which has an ESCR at condition B-10 (at 50° C.,10% IGEPAL) of less than 100 hours, and an Mz of greater than 450,000.

Inventive polyethylene compositions 1-9 (Inventive Examples 1-9) aremade using a single site phosphinimine catalyst in a dual reactorsolution process as described above and have an ESCR at condition B10 ofgreater than 20 hours and a SCB1/SCB2 ratio of greater than 0.50. Theseinventive examples also have a Mz values of less than 400,000.

Inventive polyethylene compositions 10-13 (Inventive Examples 10-13) aremade using a single site phosphinimine catalyst in a dual reactorsolution process as described above and have an ESCR at condition B10 ofgreater than 250 hours and a SCB1/SCB2 ratio of greater than 1.5. Theseinventive examples also have a Mz values of less than 450,000.

TABLE 1 Reactor Conditions for Inventive Examples Example No. InventiveInventive Inventive Inventive Inventive Example 1 Example 2 Example 3Example 4 Example 5 Reactor 1 Ethylene (kg/h) 35.6 38.1 35.7 36.7 37.51-Octene (kg/h) 4.9 4 5.3 4.1 4.8 Hydrogen (g/h) 0.51 0.58 0.51 0.500.50 Solvent (kg/h) 319.2 329 296.5 296.8 286.8 Reactor Feed Inlet 30 3030 30 30 Temperature (° C.) Reactor Temperature (° C.) 138.2 140.5 141.1143.8 149.2 Titanium Catalyst to the 0.14 0.10 0.12 0.1 0.1 Reactor(ppm) Reactor 2 Ethylene (kg/h) 43.6 51.6 43.6 44.9 45.9 1-Octene (kg/h)0 0 0 0 0 Hydrogen (g/h) 22.2 13.46 22.2 16.4 21 Solvent (kg/h) 106.7137.2 129.1 127.5 135 Reactor Feed Inlet 30 30 30 31.3 29.8 Temperature(° C.) Reactor Temperature (° C.) 186.9 192.1 186.3 190.9 194 TitaniumCatalyst to the 0.29 0.23 0.21 0.21 0.24 Reactor (ppm) Example No.Inventive Inventive Inventive Inventive Example 6 Example 7 Example 8Example 9 Reactor 1 Ethylene (kg/h) 35.7 35.6 35.7 38.4 1-Octene (kg/h)2.6 4.7 4.9 1.5 Hydrogen (g/h) 0.45 0.46 0.46 0.62 Solvent (kg/h) 256.6259.1 258.9 346.3 Reactor Feed Inlet 30 30 30 30 Temperature (° C.)Reactor Temperature (° C.) 152.5 151 147 141.1 Titanium Catalyst to the0.08 0.13 0.10 0.10 Reactor (ppm) Reactor 2 Ethylene (kg/h) 43.6 43.643.6 51.9 1-Octene (kg/h) 0 0 0 0 Hydrogen (g/h) 10.2 21.59 16.21 15.07Solvent (kg/h) 171.6 167 167.1 121.7 Reactor Feed Inlet 30 30 30 30Temperature (° C.) Reactor Temperature (° C.) 185.7 186.2 186.4 192.8Titanium Catalyst to the 0.13 0.22 0.20 0.31 Reactor (ppm) Example No.Inventive Inventive Inventive Inventive Example Example Example Example10 11 12 13 Reactor 1 Ethylene (kg/h) 34.1 34.1 34.1 32.6 1-Octene(kg/h) 4 3.1 4.8 4.9 Hydrogen (g/h) 0.27 0.22 0.35 0.29 Solvent (kg/h)331.3 345.1 314.4 311.4 Reactor Feed Inlet 30 30 30 30 Temperature (°C.) Reactor Temperature (° C.) 135.8 137 139.9 140 Titanium Catalyst tothe 0.08 0.13 0.09 0.13 Reactor (ppm) Reactor 2 Ethylene (kg/h) 41.741.7 41.7 40.0 1-Octene (kg/h) 0 0 0 0 Hydrogen (g/h) 19.8 19.25 23.1020.35 Solvent (kg/h) 128.8 115.7 144.9 151.1 Reactor Feed Inlet 29.834.2 30 30.5 Temperature (° C.) Reactor Temperature (° C.) 192.2 192191.9 186.3 Titanium Catalyst to the 0.29 0.21 0.28 0.21 Reactor (ppm)

TABLE 2 Resin Properties Example No. Comparative Comparative ComparativeComparative Comparative Example 1 Example 2 Example 3 Example 4 Example5 Density (g/cm³) 0.9534 0.9523 0.9526 0.952 0.953 Rheology/FlowProperties Melt Index I₂ (g/10 min) 1.88 0.625 1.42 1.92 0.68 Melt FlowRatio (I₂₁/I₂) 56.9 51.2 50.5 77.1 73.2 Stress Exponent 1.41 1.38 1.361.38 1.38 I₂₁ (g/10 min) 107 33.1 71.3 146.0 49.8 I₅ (g/10 min) 4.23I₂₁/I₅ 16.86 Shear Viscosity at 10⁵ s⁻¹ 5.8 (240° C., Pa-s) ShearViscosity Ratio 12.0 η(10 s⁻¹)/η(1000 s⁻¹) at 240° C. DMA Data (190° C.)η = 5832 Pa * s at G* = 2.099 kPa; η* = 5591 Pa * s at G* = 2.795 kPaGPC M_(n) 14393 22392 17827 9891 12424 M_(w) 91663 109626 105289 77319104353 M_(z) 325841 299470 282159 245479 327007 Polydispersity Index6.37 4.9 5.91 7.82 8.4 (M_(w)/M_(n)) M_(z)/M_(w) 3.55 3.56 2.68 3.173.13 Broadness Factor 1.79 1.38 2.21 2.47 2.68(M_(w)/M_(n))/(M_(z)/M_(w)) Branch Frequency - FTIR (uncorrected forchain end —CH₃) Uncorrected 2.2 2 2.2 3.7 2.5 SCB/1000C Uncorrected 0.40.4 0.4 0.7 0.5 comonomer content (mol %) Comonomer ID 1-octene 1-octene1-octene 1-octene 1-octene Comonomer mol % measured by ¹³C-NMR Hexyl+branches (≧4 0.3 0.2 0.28 carbon atoms), mol % Slow-CTREF CDBI₅₀ (wt. %)63 CDBI₂₅ (wt. %) DSC Primary Melting Peak 128.3 129.7 129.11 126.8128.42 (° C.) Heat of Fusion (J/g) 204.7 198.2 207.7 200.3 213.80Crystallinity (%) 70.58 68.34 71.61 69.08 73.72 Other properties HexaneExtractables 0.44 0.46 0.32 0.73 0.57 (wt %) VICAT Soft. Pt. (° C.) -126 127 127.3 122 125 Plaque Heat Deflection Temp. 72 71 68.2 68 71 [°C.] @ 66 PSI Example No. Comparative Comparative Inventive InventiveInventive Example 6 Example 7 Example 1 Example 2 Example 3 Density(g/cm³) 0.955 0.955 0.9529 0.9524 0.9524 Rheology/Flow Properties MeltIndex I₂ 1.5 2.5 1.57 2.94 1.69 (g/10 min) Melt Flow Ratio 66 51 58 44.161 (I₂₁/I₂) Stress Exponent 1.58 1.53 1.38 1.36 1.38 I₂₁ (g/10 min) 99113 90 129 104 I₅ (g/10 min) 5.31 7.8 4.72 4.94 I₂₁/I₅ 18.64 19.07 21.05Shear Viscosity 6.2 6.63 5.1 6.2 4.8 at 10⁵ s⁻¹ (240° C., Pa-s) ShearViscosity 11.3 9.48 13.5 8.1 13.0 Ratio η(10 s⁻¹)/ η(1000 s⁻¹) at 240°C. DMA Data η* = 5294 Pa * s η* = 4889 Pa * s (190° C.) at G* = 2.647kPa; at G* = 2.445 kPa; η* = 5106 Pa * η* = 4739 Pa * s at G* = s at G*= 3.547 kPa 3.292 kPa GPC M_(n) 10240 17100 10524 15679 10579 M_(w)106992 102000 83712 74090 86319 M_(z) 533971 470400 256210 215369 291056Polydispersity 10.45 5.96 7.95 4.73 8.16 Index (M_(w)/M_(n)) M_(z)/M_(w)4.99 4.61 3.06 2.91 3.37 Broadness 2.09 1.29 2.60 1.63 2.42 Factor(M_(w)/M_(n))/ (M_(z)/M_(w)) Branch Frequency - FTIR (uncorrected forchain end —CH₃) Uncorrected 2.3 2.5 3 1.8 3 SCB/1000C Uncorrected 0.50.5 0.6 0.4 0.6 comonomer content (mol %) Comonomer ID 1-hexene 1-hexene1-octene 1-octene 1-octene Comonomer mol % measured by ¹³C-NMR Hexyl+0.68 0.4 0.4 branches(≧4 carbon atoms), mol % Slow-CTREF CDBI₅₀ (wt. %)63.4 67.3 CDBI₂₅ (wt. %) 39 49.8 65.4 61.8 61.8 DSC Primary Melting130.06 131.24 127.3 128.8 127.5 Peak (° C.) Heat of Fusion 217.4 217.6203.8 206.1 207.3 (J/g) Crystallinity (%) 74.98 75.04 70.27 71.08 71.48Other properties Hexane 0.36 0.48 0.36 0.22 0.42 Extractables (wt %)VICAT Soft. Pt. 126.8 126.6 125.2 126.8 124.8 (° C.) - Plaque HeatDeflection 73 76.4 68 74.1 76 Temp. [° C.] @ 66 PSI Example No.Inventive Inventive Inventive Inventive Inventive Example 4 Example 5Example 6 Example 7 Example 8 Density (g/cm³) 0.9523 0.9532 0.95270.9534 0.9522 Rheology/Flow Properties Melt Index I₂ (g/10 min) 1.5 1.781.29 2.05 1.31 Melt Flow Ratio (I₂₁/I₂) 54.8 55.6 44.1 55 64 StressExponent 1.4 1.37 1.35 1.34 1.39 I₂₁ (g/10 min) 82.3 99.1 57 113 83 I₅(g/10 min) 4.5 5.33 6.21 I₂₁/I₅ 18.29 18.59 18.20 Shear Viscosity at 10⁵s⁻¹ 5.8 5.1 6.3 5.0 5.8 (240° C., Pa-s) Shear Viscosity Ratio 14.8 13.311.6 12.1 14.8 η(10 s⁻¹)/η(1000 s⁻¹) at 240° C. DMA Data (190° C.) η* =6707 η* = 6688 Pa * Pa * s at G* = s at G* = 2.413 kPa; 2.407 kPa; η* =η* = 6472 Pa * s at 6465 Pa * s G* = 3.236 kPa at G* = 3.232 kPa GPCM_(n) 13309 9716 18449 11145 14021 M_(w) 88295 84943 93080 80630 93175M_(z) 278141 288665 272788 243944 303823 Polydispersity Index 6.63 8.745.05 7.23 6.65 (M_(w)/M_(n)) M_(z)/M_(w) 3.15 3.40 2.93 3.03 3.26Broadness Factor 2.10 2.57 1.72 1.43 2.04 (M_(w)/M_(n))/(M_(z)/M_(w))Branch Frequency - FTIR (uncorrected for chain end —CH₃) Uncorrected 2.12.5 1.7 2.8 2.2 SCB/1000C Uncorrected 0.4 0.5 0.3 0.6 0.4 comonomercontent (mol %) Comonomer ID 1-octene 1-octene 1-octene 1-octene1-octene Comonomer mol % measured by ¹³C- NMR Hexyl+ branches (>=4 0.3carbon atoms), mol % Slow-CTREF CDBI₅₀ (wt. %) 76.5 75.2 86.2 79.7 80.4CDBI₂₅ (wt. %) DSC Primary Melting Peak 129 128.3 129.8 127.9 128.4 (°C.) Heat of Fusion (J/g) 209 207.3 208.5 211.1 205.4 Crystallinity (%)72.08 71.48 71.9 72.8 70.82 Other properties Hexane Extractables 0.250.33 0.25 0.38 0.27 (wt %) VICAT Soft. Pt. (° C.) - 126.4 125.4 128.2125.2 126.2 Plaque Heat Deflection Temp. 67.3 69.8 68.2 66.8 69 [° C.] @66 PSI Example No. Inventive Inventive Inventive Inventive InventiveExample 9 Example 10 Example 11 Example 12 Example 13 Density (g/cm³)0.9568 0.9545 0.9532 0.9543 0.9522 Rheology/Flow Properties Melt IndexI₂ 1.68 0.67 0.76 1.15 1.35 (g/10 min) Melt Flow Ratio 54.2 53 48.3 8488 (I₂₁/I₂) Stress Exponent 1.40 1.38 1.39 1.39 1.38 I₂₁ (g/10 min) 9153 48.3 84 88 I₅ (g/10 min) 2.14 2.36 3.54 4.12 I₆ (g/10 min) 3.07 3.55.29 6.18 I₂₁/I₅ 24.77 20.47 23.73 21.36 Shear Viscosity 6.0 4.8 5.1 4.44.6 at 10⁵ s⁻¹ (240° C., Pa-s) Shear Viscosity 11.2 22.3 19.1 17.9 14.6Ratio η(10 s⁻¹)/η (1000 s⁻¹) at 240° C. DMA Data (190° C.) GPC M_(n)15110 10953 10876 9202 9424 M_(w) 85227 112697 112804 98160 86829 M_(z)287035 388883 375939 332900 286320 Polydispersity 5.64 10.29 10.37 10.679.21 Index (M_(w)/M_(n)) M_(z)/M_(w) 3.37 3.45 3.33 3.39 3.30 Broadness1.67 2.98 3.11 3.15. 2.79 Factor (M_(w)/M_(n))/ (M_(z)/M_(w)) BranchFrequency - FTIR (uncorrected for chain end —CH₃) Uncorrected 1.3 2.52.5 2.9 3.2 SCB/1000C Uncorrected 0.3 0.5 0.5 0.6 0.6 comonomer content(mol %) Comonomer ID 1-octene 1-octene 1-octene 1-octene 1-octeneComonomer mol % measured by ¹³C-NMR Hexyl+ branches (>=4 carbon atoms),mol % Slow-CTREF CDBI₅₀ (wt. %) 77.8 73 75.7 71.9 77.3 CDBI₂₅ (wt. %)64.4 66.5 64.1 69.4 DSC Primary Melting 130.7 128.76 128.69 128.29127.52 Peak (° C.) Heat of Fusion 213.8 221.5 217.1 218.8 215.2 (J/g)Crystallinity (%) 73.73 76.39 74.86 75.45 74.22 Other properties Hexane0.24 0.40 0.30 0.53 0.46 Extractables (wt %) VICAT Soft. Pt. 128.4 126.1126.2 125.6 124.7 (° C.) - Plaque Heat Deflection 77.6 78 74.6 75.7 67.4Temp. [° C.] @ 66 PSI

TABLE 3 Polyethylene Component Properties (Comparative Examples) ExampleNo. Comparative Comparative Comparative Comparative Comparative Example1 Example 2 Example 3 Example 4 Example 5 Density (g/cm³) 0.9534 0.95230.9526 0.952 0.953 I₂ (g/10 min.) 1.88 0.625 1.42 1.92 0.68 StressExponent 1.41 1.38 1.36 1.38 1.38 MFR (I₂₁/I₂) 56.9 51.2 50.5 77.1 73.2Mw/Mn 6.37 4.9 6.34 7.82 8.39 1^(st) Ethylene Copolymer weight % 0.430.43 0.433 0.426 0.449 Mw 162400 214300 176200 169500 213200 I₂ (g/10min.) 0.13 0.05 0.10 0.11 0.05 Density 1, d₁ 0.9389 0.9356 0.9334 0.93820.9363 (g/cm³) SCB1 per 0.15 0.13 1.07 0.18 0.06 1000Cs mol % 1-octene0.03 0.03 0.21 0.04 0.01 2^(nd) Ethylene Copolymer weight % 0.57 0.570.567 0.574 0.551 Mw 18500 25600 17300 11700 14300 I₂ (g/10 min.) 736190 979 5082 2148 Density 2, d₂ 0.9559 0.9522 0.9528 0.9559 0.9565(g/cm³) SCB2 per 1.06 1.37 2.16 2.1 1.42 1000Cs mol % 1-octene 0.21 0.270.43 0.42 0.28 Estimated (d₂ − 0.017 0.0166 0.0194 0.0177 0.0202 d₁),g/cm³ Estimated (SCB2 − 0.91 1.24 1.09 1.92 1.36 SCB1) SCB1/SCB2 0.140.09 0.50 0.09 0.04 Polyethylene Component Properties (InventiveExamples) Example No. Inventive Example 3 Inventive Example 4 InventiveExample 5 Inventive Example 7 Density (g/cm³) 0.9524 0.9523 0.95320.9534 I₂ (g/10 min.) 1.69 1.5 1.78 2.05 Stress Exponent 1.38 1.4 1.371.34 MFR (I₂₁/I₂) 61 54.8 55.6 55 Mw/Mn 8.16 6.63 8.74 7.23 1^(st)Ethylene Copolymer weight % 0.455 0.454 0.454 0.453 Mw 165100 168100162700 157200 I₂ (g/10 min.) 0.13 0.12 0.13 0.15 Density 1, d₁ (g/cm³)0.9325 0.9302 0.9322 0.9316 SCB1 per 1000Cs 1.57 2.24 1.71 2.02 mol %1-octene 0.31 0.45 0.34 0.40 2^(nd) Ethylene Copolymer weight % 0.5450.546 0.546 0.547 Mw 11100 14900 12100 11400 I₂ (g/10 min.) 6318 18174419 5739 Density 2, d₂ (g/cm³) 0.9614 0.9555 0.959 0.9577 SCB2 per1000Cs 0.63 1.64 1.08 1.59 mol % 1-octene 0.13 0.33 0.22 0.32 Estimated(d₂ − d₁), 0.0289 0.0253 0.0268 0.0261 g/cm³ Estimated (SCB2 − −0.94−0.6 −0.63 −0.43 SCB1) SCB1/SCB2 2.5 1.37 1.58 1.27 Example No.Inventive Example Inventive Example Inventive Example Inventive Example10 11 12 13 Density (g/cm³) 0.9545 0.9532 0.9543 0.9522 I₂ (g/10 min.)0.67 0.76 1.15 1.35 Stress Exponent 1.38 1.39 1.39 1.38 MFR (I₂₁/I₂) 7964 73 64 Mw/Mn 10.29 10.37 10.67 9.21 1^(st) Ethylene Copolymer weight %0.429 0.464 0.423 0.433 Mw 226800 201800 199000 185900 I₂ (g/10 min.)0.04 0.06 0.06 0.08 Density 1, d₁ 0.9295 0.9299 0.9312 0.9318 (g/cm³)SCB1 per 1000Cs 1.3 1.6 1.28 1.35 mol % 1-octene 0.26 0.32 0.26 0.272^(nd) Ethylene Copolymer weight % 0.571 0.536 0.577 0.567 Mw 1090011200 9300 10000 I₂ (g/10 min.) 6980 6163 13434 10206 Density 2, d₂0.9643 0.9631 0.9639 0.9640 (g/cm³) SCB2 per 1000Cs 0.15 0.29 0.38 0.29mol % 1-octene 0.03 0.06 0.08 0.06 Estimated (d₂ − d₁), 0.0348 0.03320.0327 0.0322 g/cm³ SCB1/SCB2 8.67 5.52 3.37 4.66

TABLE 4 Plaque Properties Example No. Comparative ComparativeComparative Comparative Comparative Example 1 Example 2 Example 3Example 4 Example 5 Environmental Stress Crack Resistance ESCR Cond. B<24 <24 <24 <24 <24 at 10% (hours) Flexural Properties (Plaques) FlexSecant 1035 1070 1198 1062 1201 Mod. 1% (MPa) Flex Sec Mod 25 37 38 3441 1% (MPa) Dev. Flex Secant 877 906 1011 904 1002 Mod. 2% (MPa) FlexSec Mod 19 29 22 28 32 2% (MPa) Dev. Flexural 31.5 33.4 35.1 33 35.5Strength (MPa) Flexural 0.6 0.7 0.4 0.9 0.6 Strength Dev. (MPa) TensileProperties (Plaques) Elong. at Yield 10.2 10.3 10 10.3 10.2 (%) Elong.at Yield 0.8 1 0 0.3 0.4 Dev. (%) Yield Strength 26.6 25.4 26.3 25.726.9 (MPa) Yield Strength 0.3 0.4 0.6 0.6 0.3 Dev. (MPa) Ultimate Elong.920 1003 858 535 800 (%) Ultimate 94.6 23.7 37 167.4 86.1 Elong. Dev.(%) Ultimate 21.5 33.8 21.4 14.8 20.7 Strength (MPa) Ultimate 4.1 1.11.8 0.7 6.7 Strength Dev. (MPa) Sec Mod 1% 1374 1138 1294 1244 1237(MPa) Sec Mod 1% 276.4 210.8 188 47.1 83 (MPa) Dev. Sec Mod 2% 937 834900 858 888 (MPa) Sec Mod 2% 71 61 44 24 47 (MPa) Dev. Impact Properties(Plaques) Notched Izod 76 139 64.1 69.4 97.1 Impact (J/m) IZOD DV (J/m)7 7 5.3 6.9 2.8 Example No. Comparative Comparative Inventive InventiveInventive Example 6 Example 7 Example 1 Example 2 Example 3Environmental Stress Crack Resistance ESCR Cond. B at 10% 196 78 309 23212 (hours) Flexural Properties (Plaques) Flex Secant Mod. 1% (MPa) 13721304 1274 1247 1267 Flex Sec Mod 1% (MPa) 87 46 39 44 19 Dev. FlexSecant Mod. 2% (MPa) 1167 1102 1064 1035 1060 Flex Sec Mod 2% (MPa) 4541 29 33 14 Dev. Flexural Strength (MPa) 40.4 38.3 37.5 36.7 37.1Flexural Strength Dev. 1 0.6 0.8 0.4 0.3 (MPa) Tensile Properties(Plaques) Elong. at Yield (%) 9 9 9 10 8 Elong. at Yield Dev. (%) 1 1 11 0 Yield Strength (MPa) 28.5 26.4 26 25.6 26.4 Yield Strength Dev.(MPa) 0.3 0.3 0.2 0.1 0.3 Ultimate Elong. (%) 870 1055 701 988 762Ultimate Elong. Dev. (%) 69 42 106 58 98 Ultimate Strength (MPa) 26.831.6 21.8 32.2 24.7 Ultimate Strength Dev. 5.5 1 6.8 1.9 7.4 (MPa) SecMod 1% (MPa) 1696 1545 1483 1256 1331 Sec Mod 1% (MPa) Dev. 279 231 121333 241 Sec Mod 2% (MPa) 1118 993 973 880 939 Sec Mod 2% (MPa) Dev. 9091 33 88 62 Impact Properties (Plaques) Notched Izod Impact 80.1 80 74.769.4 69.4 (J/m) IZOD DV (J/m) 5.3 0.0 0.0 0.0 Example No. InventiveInventive Inventive Inventive Inventive Example 4 Example 5 Example 6Example 7 Example 8 Environmental Stress Crack Resistance ESCR Cond. Bat 10% 86 83 60 73 157 (hours) Flexural Properties (Plaques) Flex SecantMod. 1% (MPa) 1295 1304 1240 1318 1260 Flex Sec Mod 1% (MPa) Dev. 23 5731 37 25 Flex Secant Mod. 2% (MPa) 1085 1092 1026 1098 1049 Flex Sec Mod2% (MPa) Dev. 21 40 26 24 15 Flexural Strength (MPa) 37.3 37.6 36.1 38.236.9 Flexural Strength Dev. (MPa) 0.4 0.8 0.6 0.3 0.6 Tensile Properties(Plaques) Elong. at Yield (%) 10 9 10 8 9 Elong. at Yield Dev. (%) 0 0 00 1 Yield Strength (MPa) 26.3 26.4 25.6 26.9 26.1 Yield Strength Dev.(MPa) 0.3 0.2 0.2 0.2 0.2 Ultimate Elong. (%) 891 862 974 766 836Ultimate Elong. Dev. (%) 23 47 35 130 103 Ultimate Strength (MPa) 33.329.7 36.3 22.9 29.6 Ultimate Strength Dev. (MPa) 2 2.7 1.5 7 5.5 Sec Mod1% (MPa) 1230 1197 1333 1429 1395 Sec Mod 1% (MPa) Dev. 90 128 213 183217 Sec Mod 2% (MPa) 913 881 893 979 934 Sec Mod 2% (MPa) Dev. 34 40 7052 73 Impact Properties (Plaques) Notched Izod Impact (J/m) 80.1 64.1128.1 64.1 80.1 IZOD DV (J/m) 2.7 2.1 5.3 0.0 0.0 Example No. InventiveInventive Inventive Inventive Inventive Example 9 Example 10 Example 11Example 12 Example 13 Environmental Stress Crack Resistance ESCR Cond. Bat 10% 24 1100 720 399 to 484 655 (hours) Flexural Properties (Plaques)Flex Secant Mod. 1% (MPa) 1402 1341 1330 1354 1297 Flex Sec Mod 1% (MPa)48 34 30 34 27 Dev. Flex Secant Mod. 2% (MPa) 1159 1131 1119 1138 1095Flex Sec Mod 2% (MPa) 35 26 22 26 16 Dev. Flexural Strength (MPa) 39.839.1 38.4 38.7 38.1 Flexural Strength Dev. (MPa) 1.1 0.4 0.5 0.4 0.6Tensile Properties (Plaques) Elong. at Yield (%) 10 9 8 8 9 Elong. atYield Dev. (%) 0 1 1 1 1 Yield Strength (MPa) 28.2 27.2 26.9 27.7 26.1Yield Strength Dev. (MPa) 0.6 0.5 0.4 0.5 0.5 Ultimate Elong. (%) 923810 821 747 694 Ultimate Elong. Dev. (%) 104 73 103 94 95 UltimateStrength (MPa) 26.9 33 33.2 24.3 23 Ultimate Strength Dev. 6.9 5.7 8.47.4 6.9 (MPa) Sec Mod 1% (MPa) 1367 1586 1624 1506 1358 Sec Mod 1% (MPa)Dev. 190 258 323 369 207 Sec Mod 2% (MPa) 966 1031 1031 1034 950 Sec Mod2% (MPa) Dev. 67 65 97 113 48 Impact Properties (Plaques) Notched IzodImpact (J/m) 90.7 107.0 107.0 69.4 80.0 IZOD DV (J/m) 5.3 5.3 5.3 0.05.3

As can be seen from the data provided in Tables 2, 3 and 4, theInventive polyethylene compositions (Inventive Examples 1-9) which havea ratio of short chain branching SCB1/SCB2 of greater than 0.5, haveimproved ESCR B properties while maintaining good processability.

As shown in FIG. 1, inventive polyethylene compositions 1, 10, 11 and 13provide an improved balance of ESCR and stiffness (as indicated by 2%secant floral modulus) when compared to comparative polyethylenecompositions 6, and 7.

As shown in FIG. 2, inventive polyethylene compositions 1, 10, 11 and 13provide an improved balance of ESCR and processability (as indicated bythe “shear viscosity ratio”) when compared to comparative polyethylenecompositions 6 and 7.

As shown in FIG. 3, inventive polyethylene compositions 1, 10, 11 and 13provide an improved balance of processability (as indicated by the“shear viscosity ratio”) and Notched Izod Impact Strength, when comparedto comparative polyethylene compositions 6 and 7.

FIG. 4 shows that inventive polyethylene compositions 1, 10, 11 and 13have an improved balance of processability (as indicated by the “shearviscosity ratio”) and stiffness (as indicated by 2% secant floralmodulus) when compared to comparative polyethylene compositions 6, and7.

As shown in FIG. 5, the inventive polyethylene compositions 1, 3, 5, 6and 8 do not satisfy the equation SHI_((1,100))≧−10.58 (log I₂ of thepolyethylene composition in g/10 min)/(g/10 min)+12.94, which is aproperty of the blends taught in WO 2006/048253. As shown in FIG. 5, theinventive polyethylene compositions 1, 3, 5, 6 and 8 do not satisfy theequation:

SHI_((1,100))≧−5.5(log I ₂ of the polyethylene composition in g/10min)/(g/10 min)+9.66,

which is a property of the blends taught in and WO 2006/048254.

FIG. 6 shows the bimodal nature of the inventive polyethylenecompositions 10-13. Each ethylene copolymer component has a M_(w)/M_(n)value of less than 2.5.

As shown in FIG. 7, the inventive polyethylene compositions 10-13 do notsatisfy the equation SHI_((1,100))≧−10.58 (log I₂ of the polyethylenecomposition in g/10 min)/(g/10 min)+12.94, which is a property of theblends taught in WO 2006/048253. As shown in FIG. 7, the inventivepolyethylene compositions 10-13 do not satisfy the equation:SHI_((1,100))≧−5.5 (log I₂ of the polyethylene composition in g/10min)/(g/10 min)+9.66, which is a property of the blends taught in and WO2006/048254.

What is claimed is:
 1. A closure, said closure comprising a bimodalpolyethylene composition comprising: (1) 10 to 70 weight percent of afirst ethylene copolymer having a melt index I₂, of less than 0.4 g/10min; a molecular weight distribution M_(w)/M_(n), of less than 2.7; anda density of from 0.920 to 0.955 g/cm³; and (2) 90 to 30 weight percentof a second ethylene copolymer having a melt index I₂, of from greaterthan 500 to 20,000 g/10 min; a molecular weight distributionM_(w)/M_(n), of less than 2.7; and a density higher than the density ofsaid first ethylene copolymer, but less than 0.967 g/cm³; wherein thedensity of said second ethylene copolymer is less than 0.037 g/cm³higher than the density of said first ethylene copolymer; the ratio(SCB1/SCB2) of the number of short chain branches per thousand carbonatoms in said first ethylene copolymer (SCB1) to the number of shortchain branches per thousand carbon atoms in said second ethylenecopolymer (SCB2) is greater than 1.0; and wherein said bimodalpolyethylene composition has a molecular weight distributionM_(w)/M_(n), of from 6 to 13; a density of at least 0.949 g/cm³; a meltindex I₂, of from 0.2 to 3.0 g/10 min; an M_(z) of less than 450,000; astress exponent of less than 1.50, and an ESCR Condition B (10% IGEPAL)of at least 200 hours.
 2. The closure of claim 1 wherein said bimodalpolyethylene composition has an ESCR Condition B (10% IGEPAL) of atleast 350 hours.
 3. The closure of claim 1 wherein said bimodalpolyethylene composition has a molecular weight distribution,M_(w)/M_(n), of from 8 to
 12. 4. The closure of claim 1 wherein saidbimodal polyethylene composition has melt index I₂, of from 0.4 to 2.0g/10 min.
 5. The closure of claim 1 wherein the second ethylenecopolymer has a melt index I₂ of greater than 650 g/10 min.
 6. Theclosure of claim 1 wherein said bimodal polyethylene composition has az-average molecular weight distribution, Mz/Mw of less than 4.0.
 7. Theclosure of claim 1 wherein said first ethylene copolymer has a densityof from 0.925 to 0.950 g/cm³.
 8. The closure of claim 1 wherein saidsecond ethylene copolymer has a density of less than 0.965 g/cm³.
 9. Theclosure of claim 1 wherein said bimodal polyethylene composition has adensity of from 0.951 to 0.957 g/cm³.
 10. The closure of claim 1 whereinthe density of said second ethylene copolymer is less than 0.035 g/cm³higher than the density of said first ethylene copolymer.
 11. Theclosure of claim 1 wherein said first and second ethylene copolymershave a M_(w)/M_(n) of less than 2.5.
 12. The closure of claim 1 whereinsaid bimodal polyethylene composition has a composition distributionbreadth index (CDBI₂₅) of greater than 55% by weight.
 13. The closure ofclaim 1 wherein the second ethylene copolymer has a melt index, I₂ offrom 1,000 to 20,000.
 14. The closure of claim 1 wherein the ratio(SCB1/SCB2) of the number of short chain branches per thousand carbonatoms in said first ethylene copolymer (SCB1) to the number of shortchain branches per thousand carbon atoms in said second ethylenecopolymer (SCB2) is greater than 1.5.
 15. The closure of claim 1 whereinsaid bimodal polyethylene composition has a broadness factor defined as(M_(w)/M_(n))/(M_(z)/M_(w)) of at least 2.75.
 16. The closure of claim 1wherein the ratio (SCB1/SCB2) of the number of short chain branches perthousand carbon atoms in said first ethylene copolymer (SCB1) to thenumber of short chain branches per thousand carbon atoms in said secondethylene copolymer (SCB2) is greater than 3.0.
 17. The closure of claim1 wherein said bimodal polyethylene composition comprises: from 30 to 60weight percent of said first ethylene copolymer; and from 70 to 40weight percent of said second ethylene copolymer.
 18. The closure ofclaim 1 wherein the bimodal polyethylene composition further comprises anucleating agent or a mixture of nucleating agents.
 19. The closure ofclaim 1 wherein said first and second ethylene copolymers are copolymersof ethylene and 1-octene.
 20. The closure of claim 1 wherein saidclosure is made by compression molding or injection molding.
 21. Theclosure of claim 1 wherein said closure is a screw cap.
 22. A process toprepare a polyethylene composition, said polyethylene compositioncomprising: (1) 10 to 70 weight percent of a first ethylene copolymerhaving a melt index I₂, of less than 0.4 g/10 min; a molecular weightdistribution M_(w)/M_(n), of less than 2.7; and a density of from 0.920to 0.955 g/cm³; and (2) 90 to 30 weight percent of a second ethylenecopolymer having a melt index I₂, of from greater than 500 to 20,000g/10 min; a molecular weight distribution M_(w)/M_(n), of less than 27;and a density higher than the density of said first ethylene copolymer,but less than 0.967 g/cm³; wherein the density of said second ethylenecopolymer is less than 0.037 g/cm³ higher than the density of said firstethylene copolymer; the ratio (SCB1/SCB2) of the number of short chainbranches per thousand carbon atoms in said first ethylene copolymer(SCB1) to the number of short chain branches per thousand carbon atomsin said second ethylene copolymer (SCB2) is greater than 1.0; andwherein said bimodal polyethylene composition has a molecular weightdistribution M_(w)/M_(n), of from 6 to 13; a density of at least 0.949g/cm³; a melt index I₂, of from 0.2 to 3.0 g/10 min; an M_(z) of lessthan 450,000; a stress exponent of less than 1.50, and an ESCR ConditionB (10% IGEPAL) of at least 200 hours; said process comprising contactingat least one single site polymerization catalyst system with ethyleneand at least one alpha-olefin under solution polymerization conditionsin at least two polymerization reactors.
 23. The process of claim 22wherein said at least two polymerization reactors comprise a firstreactor and a second reactor configured in series.
 24. The process ofclaim 22 wherein said at least two polymerization reactors comprise afirst reactor and a second reactor configured in parallel.
 25. Theprocess of claim 23 wherein said at least one alpha-olefin is fedexclusively to said first reactor.
 26. A bimodal polyethylenecomposition comprising: (1) 10 to 70 weight percent of a first ethylenecopolymer having a melt index I₂, of less than 0.4 g/10 min; a molecularweight distribution M_(w)/M_(n), of less than 2.7; and a density of from0.920 to 0.955 g/cm³; and (2) 90 to 30 weight percent of a secondethylene copolymer having a melt index I₂, of from greater than 500 to20,000 g/10 min; a molecular weight distribution M_(w)/M_(n), of lessthan 2.7; and a density higher than the density of said first ethylenecopolymer, but less than 0.967 g/cm³; wherein the density of said secondethylene copolymer is less than 0.037 g/cm³ higher than the density ofsaid first ethylene copolymer; the ratio (SCB1/SCB2) of the number ofshort chain branches per thousand carbon atoms in said first ethylenecopolymer (SCB1) to the number of short chain branches per thousandcarbon atoms in said second ethylene copolymer (SCB2) is greater than1.0; and wherein said bimodal polyethylene composition has a molecularweight distribution M_(w)/M_(n), of from 6 to 13; a density of at least0.949 g/cm³; a melt index I₂, of from 0.2 to 3.0 g/10 min; an M_(z) ofless than 450,000; a stress exponent of less than 1.50, and an ESCRCondition B (10% IGEPAL) of at least 200 hours.
 27. The bimodalpolyethylene composition of claim 26 wherein said bimodal polyethylenecomposition has an ESCR Condition B (10% IGEPAL) of at least 350 hours.28. The bimodal polyethylene composition of claim 26 wherein saidbimodal polyethylene composition has a molecular weight distribution,M_(w)/M_(n), of from 8 to
 12. 29. The bimodal polyethylene compositionof claim 26 wherein said bimodal polyethylene composition has melt indexI₂, of from 0.4 to 2.0 g/10 min.
 30. The bimodal polyethylenecomposition of claim 26 wherein the second ethylene copolymer has a meltindex I₂ of greater than 650 g/10 min.
 31. The bimodal polyethylenecomposition of claim 26 wherein said bimodal polyethylene compositionhas a z-average molecular weight distribution, Mz/Mw of less than 4.032. The bimodal polyethylene composition of claim 26 wherein said firstethylene copolymer has a density of from 0.925 to 0.950 g/cm³.
 33. Thebimodal polyethylene composition of claim 26 wherein said secondethylene copolymer has a density of less than 0.965 g/cm³.
 34. Thebimodal polyethylene composition of claim 26 wherein said bimodalpolyethylene composition has a density of from 0.951 to 0.957 g/cm³. 35.The bimodal polyethylene composition of claim 26 wherein the density ofsaid second ethylene copolymer is less than 0.035 g/cm³ higher than thedensity of said first ethylene copolymer.
 36. The bimodal polyethylenecomposition of claim 26 wherein said first and second ethylenecopolymers have a M_(w)/M_(n) of less than 2.5.
 37. The bimodalpolyethylene composition of claim 26 wherein said bimodal polyethylenecomposition has a composition distribution breadth index (CDBI₂₅) ofgreater than 55% by weight.
 38. The bimodal polyethylene composition ofclaim 26 wherein the second ethylene copolymer has a melt index, I₂ offrom 1,000 to 20,000.
 39. The bimodal polyethylene composition of claim26 wherein the ratio (SCB1/SCB2) of the number of short chain branchesper thousand carbon atoms in said first ethylene copolymer (SCB1) to thenumber of short chain branches per thousand carbon atoms in said secondethylene copolymer (SCB2) is greater than 1.5.
 40. The bimodalpolyethylene composition of claim 26 wherein said bimodal polyethylenecomposition comprises: from 30 to 60 weight percent of said firstethylene copolymer; and from 70 to 40 weight percent of said secondethylene copolymer.
 41. The bimodal polyethylene composition of claim 26wherein said bimodal polyethylene composition has a shear viscosityratio of ≧12.5.
 42. The bimodal polyethylene composition of claim 27wherein said bimodal polyethylene composition has a shear viscosityratio of 12.5.
 43. The bimodal polyethylene composition of claim 26wherein said bimodal polyethylene composition has a broadness factordefined as (M_(w)/M_(n))/(M_(z)/M_(w)) of at least 2.75.
 44. The bimodalpolyethylene composition of claim 26 wherein the ratio (SCB1/SCB2) ofthe number of short chain branches per thousand carbon atoms in saidfirst ethylene copolymer (SCB1) to the number of short chain branchesper thousand carbon atoms in said second ethylene copolymer (SCB2) isgreater than 3.0.